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Wendorf KA, Ng R, Stainken C, Haddix M, Peterson E, Watson J, Sachdev D. Household Transmission of Mpox to Children and Adolescents, California, 2022. J Infect Dis 2024; 229:S203-S206. [PMID: 37831784 DOI: 10.1093/infdis/jiad448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 10/03/2023] [Accepted: 10/09/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND In California, the 2022 mpox outbreak cumulated 5572 cases, 20% of US cases, as of November 28, 2022; 0.3% of cases were among children <16 years old. The secondary attack rate (SAR) for children sharing households with infected adults is unknown. METHODS A line list of pediatric mpox household contacts aged <16 years reported through August 31, 2022 was created. It included demographic and clinical information on the contacts. Pediatric contact lists were crossmatched with the state vaccination database to identify those who received postexposure prophylaxis (PEP) with the JYNNEOS vaccine. RESULTS We identified 129 pediatric household contacts with median age of 7 years (range, 0-15 years). Among 18 symptomatic contacts, 12 (66.7%) underwent mpox testing; 5 (41.2%) were confirmed cases, 6 (50%) were negative, and 1 (0.8%) had an indeterminate result. Six symptomatic children were not tested for mpox (33.3%). Overall, 6 infected contacts were identified, resulting in a SAR of 4.7% (6 of 129). The majority of pediatric household contacts and 4 of 6 infected children identified as Hispanic/Latino. Only 18 children (14%) reported receiving PEP. CONCLUSIONS The SAR was overall low among pediatric household contacts; none had severe disease. This may be underestimated given low testing rates.
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Affiliation(s)
| | - Rilene Ng
- California Department of Public Health, Richmond, California, USA
| | - Cameron Stainken
- California Department of Public Health, Richmond, California, USA
| | - Meredith Haddix
- Los Angeles County Department of Public Health, Los Angeles, California, USA
| | - Erin Peterson
- Los Angeles County Department of Public Health, Los Angeles, California, USA
| | - Jessica Watson
- California Department of Public Health, Richmond, California, USA
| | - Darpun Sachdev
- California Department of Public Health, Richmond, California, USA
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Clifford S, Waight P, Hackman J, Hué S, Gower CM, Kirsebom FCM, Skarnes C, Letley L, Lopez Bernal J, Andrews N, Flasche S, Miller E. Effectiveness of BNT162b2 and ChAdOx1 against SARS-CoV-2 household transmission: a prospective cohort study in England. Wellcome Open Res 2023; 8:96. [PMID: 38058535 PMCID: PMC10697107 DOI: 10.12688/wellcomeopenres.17995.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2023] [Indexed: 12/08/2023] Open
Abstract
Background The ability of SARS-CoV-2 vaccines to protect against infection and onward transmission determines whether immunisation can control global circulation. We estimated the effectiveness of Pfizer-BioNTech mRNA vaccine (BNT162b2) and Oxford AstraZeneca adenovirus vector vaccine (ChAdOx1) vaccines against acquisition and transmission of the Alpha and Delta variants in a prospective household study in England. Methods Households were recruited based on adult purported index cases testing positive after reverse transcription-quantitative (RT-q)PCR testing of oral-nasal swabs. Purported index cases and their household contacts took oral-nasal swabs on days 1, 3 and 7 after enrolment and a subset of the PCR-positive swabs underwent genomic sequencing conducted on a subset. We used Bayesian logistic regression to infer vaccine effectiveness against acquisition and transmission, adjusted for age, vaccination history and variant. Results Between 2 February 2021 and 10 September 2021, 213 index cases and 312 contacts were followed up. After excluding households lacking genomic proximity (N=2) or with unlikely serial intervals (N=16), 195 households with 278 contacts remained, of whom 113 (41%) became PCR positive. Delta lineages had 1.53 times the risk (95% Credible Interval: 1.04 - 2.20) of transmission than Alpha; contacts older than 18 years old were 1.48 (1.20 - 1.91) and 1.02 (0.93 - 1.16) times more likely to acquire an Alpha or Delta infection than children. Effectiveness of two doses of BNT162b2 against transmission of Delta was 36% (-1%, 66%) and 49% (18%, 73%) for ChAdOx1, similar to their effectiveness for Alpha. Protection against infection with Alpha was higher than for Delta, 69% (9%, 95%) vs. 18% (-11%, 59%), respectively, for BNT162b2 and 24% (-41%, 72%) vs. 9% (-15%, 42%), respectively, for ChAdOx1. Conclusions BNT162b2 and ChAdOx1 reduce transmission of the Delta variant from breakthrough infections in the household setting, although their protection against infection within this setting is low.
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Affiliation(s)
- Samuel Clifford
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Pauline Waight
- National Infection Service, UK Health Security Agency, London, NW9 5EQ, UK
| | - Jada Hackman
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Stephane Hué
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Charlotte M. Gower
- National Infection Service, UK Health Security Agency, London, NW9 5EQ, UK
| | - Freja CM Kirsebom
- National Infection Service, UK Health Security Agency, London, NW9 5EQ, UK
| | - Catriona Skarnes
- National Infection Service, UK Health Security Agency, London, NW9 5EQ, UK
| | - Louise Letley
- National Infection Service, UK Health Security Agency, London, NW9 5EQ, UK
| | - Jamie Lopez Bernal
- National Infection Service, UK Health Security Agency, London, NW9 5EQ, UK
| | - Nick Andrews
- National Infection Service, UK Health Security Agency, London, NW9 5EQ, UK
| | - Stefan Flasche
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Elizabeth Miller
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
- National Infection Service, UK Health Security Agency, London, NW9 5EQ, UK
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3
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Frutos AM, Kuan G, Lopez R, Ojeda S, Shotwell A, Sanchez N, Saborio S, Plazaola M, Barilla C, Kenah E, Balmaseda A, Gordon A. Infection-Induced Immunity Is Associated With Protection Against Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Decreased Infectivity. Clin Infect Dis 2023; 76:2126-2133. [PMID: 36774538 PMCID: PMC10273383 DOI: 10.1093/cid/ciad074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/24/2023] [Accepted: 02/08/2023] [Indexed: 02/13/2023] Open
Abstract
BACKGROUND The impact of infection-induced immunity on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission has not been well established. Here we estimate the effects of prior infection induced immunity in adults and children on SARS-CoV-2 transmission in households. METHODS We conducted a household cohort study from March 2020-November 2022 in Managua, Nicaragua; following a housheold SARS-CoV-2 infection, household members are closely monitored for infection. We estimate the association of time period, age, symptoms, and prior infection with secondary attack risk. RESULTS Overall, transmission occurred in 70.2% of households, 40.9% of household contacts were infected, and the secondary attack risk ranged from 8.1% to 13.9% depending on the time period. Symptomatic infected individuals were more infectious (rate ratio [RR] 21.2, 95% confidence interval [CI]: 7.4-60.7) and participants with a prior infection were half as likely to be infected compared to naïve individuals (RR 0.52, 95% CI:.38-.70). In models stratified by age, prior infection was associated with decreased infectivity in adults and adolescents (secondary attack risk [SAR] 12.3, 95% CI: 10.3, 14.8 vs 17.5, 95% CI: 14.8, 20.7). However, although young children were less likely to transmit, neither prior infection nor symptom presentation was associated with infectivity. During the Omicron era, infection-induced immunity remained protective against infection. CONCLUSIONS Infection-induced immunity is associated with decreased infectivity for adults and adolescents. Although young children are less infectious, prior infection and asymptomatic presentation did not reduce their infectivity as was seen in adults. As SARS-CoV-2 transitions to endemicity, children may become more important in transmission dynamics.
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Affiliation(s)
- Aaron M Frutos
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Guillermina Kuan
- Health Center Sócrates Flores Vivas, Ministry of Health, Managua, Nicaragua
- Sustainable Sciences Institute, Managua, Nicaragua
| | - Roger Lopez
- Sustainable Sciences Institute, Managua, Nicaragua
- Laboratorio Nacional de Virología, Centro Nacional de Diagnóstico y Referencia, Ministry of Health, Managua, Nicaragua
| | - Sergio Ojeda
- Sustainable Sciences Institute, Managua, Nicaragua
| | - Abigail Shotwell
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Nery Sanchez
- Sustainable Sciences Institute, Managua, Nicaragua
| | - Saira Saborio
- Laboratorio Nacional de Virología, Centro Nacional de Diagnóstico y Referencia, Ministry of Health, Managua, Nicaragua
- Sustainable Sciences Institute, Managua, Nicaragua
| | | | | | - Eben Kenah
- Biostatistics Division, College of Public Health, The Ohio State University, Columbus, Ohio, USA
| | - Angel Balmaseda
- Sustainable Sciences Institute, Managua, Nicaragua
- Laboratorio Nacional de Virología, Centro Nacional de Diagnóstico y Referencia, Ministry of Health, Managua, Nicaragua
| | - Aubree Gordon
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
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Islam F, Alvi Y, Ahmad M, Ahmed F, Rahman A, Singh FHD, Das AK, Dudeja M, Gupta E, Agarwalla R, Alam I, Roy S. Household transmission dynamics of COVID-19 among residents of Delhi, India: a prospective case-ascertained study. IJID Reg 2023; 7:22-30. [PMID: 36852156 PMCID: PMC9946776 DOI: 10.1016/j.ijregi.2023.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 02/25/2023]
Abstract
Objective The aim of this study was to observe the secondary infection rate and transmission dynamics of COVID-19 among household contacts, and their associations with various factors across four dimensions of interaction. Methods This was a case-ascertained study among unvaccinated household contacts of a laboratory-confirmed COVID-19 case in New Delhi between December 2020 and July 2021. For this study, 99 index cases and their 316 household contacts were interviewed and sampled (blood and oro-nasal swab) on days 1, 7, 14, and 28. Results The secondary infection rate among unvaccinated household contacts was 44.6% (95% confidence interval (CI) 39.1-50.1). The predictors of secondary infection among individual contact levels were: being female (odds ratio (OR) 2.13), increasing age (OR 1.01), symptoms at baseline (OR 3.39), and symptoms during follow-up (OR 3.18). Among index cases, age of the primary case (OR 1.03) and symptoms during follow-up (OR 6.29) were significantly associated with secondary infection. Among household-level and contact patterns, having more rooms (OR 4.44) and taking care of the index case (OR 2.02) were significantly associated with secondary infection. Conclusion A high secondary infection rate highlights the need to adopt strict measures and advocate COVID-19-appropriate behaviors. A targeted approach for higher-risk household contacts would efficiently limit infections among susceptible contacts.
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Affiliation(s)
- Farzana Islam
- Department of Community Medicine, Hamdard Institute of Medical Science and Research, New Delhi, India
| | - Yasir Alvi
- Department of Community Medicine, Hamdard Institute of Medical Science and Research, New Delhi, India
| | | | - Faheem Ahmed
- Department of Community Medicine, Hamdard Institute of Medical Science and Research, New Delhi, India.,Department of Public Health, King Khalid University, Abha, Kingdom of Saudi Arabia
| | | | - Farishta Hannah D Singh
- Department of Community Medicine, Hamdard Institute of Medical Science and Research, New Delhi, India
| | - Ayan Kumar Das
- Department of Microbiology, Hamdard Institute of Medical Science and Research, New Delhi, India
| | - Mridu Dudeja
- Department of Microbiology, Hamdard Institute of Medical Science and Research, New Delhi, India
| | - Ekta Gupta
- Scientist-E, National Institute of Cancer Prevention and Research, ICMR, Noida, India
| | - Rashmi Agarwalla
- Department of Community and Family Medicine, All India Institute of Medical Science, Guwahati, India
| | - Iqbal Alam
- Department of Physiology, Hamdard Institute of Medical Science and Research, New Delhi, India
| | - Sushovan Roy
- Department of Community Medicine, Hamdard Institute of Medical Science and Research, New Delhi, India
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Narayan A, Saraswati U, Kaur I, Kumari A, Kumar A, Vishwakarma VK, Kumar U, Sahoo V, Wig N. Household secondary attack rate in mild COVID-19. J Family Med Prim Care 2023; 12:743-747. [PMID: 37312765 PMCID: PMC10259546 DOI: 10.4103/jfmpc.jfmpc_156_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/17/2022] [Accepted: 01/20/2023] [Indexed: 06/15/2023] Open
Abstract
Background The coronavirus disease 2019 (COVID-19) pandemic has reached a staggering number of almost 280 million cases worldwide, with over 5.4 million deaths as of 29 December 2021. A further understanding of the factors related to the household spread of the infection might help to bring about specific protocols to curb such transmission. Objective This study aims to find the secondary attack rate (SAR) and factors affecting SAR among the households of mild COVID-19 cases. Methods An observational study was designed where data of patients admitted at All India Institute of Medical Sciences, New Delhi due to mild COVID-19 were collected, and outcome was noted after the discharge of the patient. Index cases who were the first in the household to have a positive infection only were included. Based on these data, the overall household SAR, factors related to the index case and contacts that affected transmissibility were noted. Results A total of 60 index cases having contacts with 184 household members were included in the present study. The household SAR was measured to be 41.85%. At least one positive case was present in 51.67% households. Children below 18 years old had lower odds of getting a secondary infection compared to adults and elderly [odds ratio (OR) = 0.46, 95%CI = 0.22-0.94, p = 0.0383). An exposure period of more than a week was significantly associated with a higher risk of infection (p = 0.029). The rate of transmissibility drastically declined with effective quarantine measures adopted by the index case (OR = 0.13, 95%CI = 0.06-0.26, p < 0.00001). Symptomatic index cases contributed more to the SAR than asymptomatic primaries (OR = 4.74, 95%CI = 1.03-21.82, P = 0.045). Healthcare worker index cases had lower rates of spread (OR = 0.29, 95%CI = 0.15-0.58, P = 0.0003). Conclusion The high SAR shows the household is a potential high-risk unit for transmissibility of COVID-19. Proper quarantine measures of all those exposed to the index case can mitigate such spread and lead to reduction of risk of COVID-19 within a household.
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Affiliation(s)
- Ananthu Narayan
- Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Ushasi Saraswati
- Department of Medicine, Maulana Azad Medical College, Delhi, India
| | - Ishmeet Kaur
- Department of Pharmacology, All India Institute of Medical Sciences, New Delhi, India
| | - Aakansha Kumari
- Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Arvind Kumar
- Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
| | | | - Upendra Kumar
- Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Vishwajeet Sahoo
- Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India
| | - Naveet Wig
- Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
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Sieber J, Schmidthaler K, Kopanja S, Weseslindtner L, Stiasny K, Götzinger F, Graf A, Krotka P, Hoz J, Schoof A, Dwivedi V, Frischer T, Szépfalusi Z. Limited role of children in transmission of SARS-CoV-2 virus in households-Immunological analysis of 26 familial clusters. Pediatr Allergy Immunol 2023; 34:e13913. [PMID: 36705043 PMCID: PMC10107319 DOI: 10.1111/pai.13913] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/23/2022] [Accepted: 01/03/2023] [Indexed: 01/28/2023]
Abstract
BACKGROUND The impact of children on the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains uncertain. This study provides an insight into distinct patterns of SARS-CoV-2 household transmission in case of pediatric and adult index cases as well as age-dependent susceptibility to SARS-CoV-2 infection. METHODS Immune analysis, medical interviewing, and contact tracing of 26 families with confirmed SARS-CoV-2 infection cases have been conducted. Blood samples were analyzed serologically with the use of a SARS-CoV-2-specific IgG assay and virus neutralization test (VNT). Uni- and multivariable linear regression and mixed effect logistic regression models were used to describe potential risk factors for higher contagiousness and susceptibility to SARS-CoV-2 infection. RESULTS SARS-CoV-2 infection could be confirmed in 67 of 124 family members. Fourteen children and 11 adults could be defined as index cases in their households. Forty of 82 exposed family members were defined as secondarily infected. The mean secondary attack rate in households was 0.48 and was significantly higher in households with adult than with pediatric index cases (0.85 vs 0.19; p < 0.0001). The age (grouped into child and adult) of index case, severity of disease, and occurrence of lower respiratory symptoms in index cases were significantly associated with secondary transmission rates in households. Children seem to be equally susceptible to acquire a SARS-CoV-2 infection as adults, but they suffer milder courses of the disease or remain asymptomatic. CONCLUSION SARS-CoV-2 transmission from infected children to other household members occurred rarely in the first wave of the pandemic, despite close physical contact and the lack of hygienic measures.
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Affiliation(s)
- Justyna Sieber
- Division of Paediatric Pulmonology, Allergy and Endocrinology, Department of Paediatrics and Adolescent Medicine, Comprehensive Centre of Paediatrics, Medical University of Vienna, Vienna, Austria.,Department of Clinical Immunology, Wroclaw Medical University, Wroclaw, Poland
| | - Klara Schmidthaler
- Division of Paediatric Pulmonology, Allergy and Endocrinology, Department of Paediatrics and Adolescent Medicine, Comprehensive Centre of Paediatrics, Medical University of Vienna, Vienna, Austria
| | - Sonja Kopanja
- Division of Paediatric Pulmonology, Allergy and Endocrinology, Department of Paediatrics and Adolescent Medicine, Comprehensive Centre of Paediatrics, Medical University of Vienna, Vienna, Austria
| | | | - Karin Stiasny
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Florian Götzinger
- Department of Paediatrics and Adolescent Medicine, Klinik Ottakring, Vienna, Austria
| | - Alexandra Graf
- Section for Medical Statistics, Center for Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Austria
| | - Pavla Krotka
- Section for Medical Statistics, Center for Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Austria
| | - Jakub Hoz
- Division of Paediatric Pulmonology, Allergy and Endocrinology, Department of Paediatrics and Adolescent Medicine, Comprehensive Centre of Paediatrics, Medical University of Vienna, Vienna, Austria
| | - Anja Schoof
- Division of Paediatric Pulmonology, Allergy and Endocrinology, Department of Paediatrics and Adolescent Medicine, Comprehensive Centre of Paediatrics, Medical University of Vienna, Vienna, Austria
| | - Varsha Dwivedi
- Division of Paediatric Pulmonology, Allergy and Endocrinology, Department of Paediatrics and Adolescent Medicine, Comprehensive Centre of Paediatrics, Medical University of Vienna, Vienna, Austria
| | | | - Zsolt Szépfalusi
- Division of Paediatric Pulmonology, Allergy and Endocrinology, Department of Paediatrics and Adolescent Medicine, Comprehensive Centre of Paediatrics, Medical University of Vienna, Vienna, Austria
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7
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Wang C, Huang X, Lau EHY, Cowling BJ, Tsang TK. Association Between Population-Level Factors and Household Secondary Attack Rate of SARS-CoV-2: A Systematic Review and Meta-analysis. Open Forum Infect Dis 2022; 10:ofac676. [PMID: 36655186 PMCID: PMC9835764 DOI: 10.1093/ofid/ofac676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Background Accurate estimation of household secondary attack rate (SAR) is crucial to understand the transmissibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The impact of population-level factors, such as transmission intensity in the community, on SAR estimates is rarely explored. Methods In this study, we included articles with original data to compute the household SAR. To determine the impact of transmission intensity in the community on household SAR estimates, we explored the association between SAR estimates and the incidence rate of cases by country during the study period. Results We identified 163 studies to extract data on SARs from 326 031 cases and 2 009 859 household contacts. The correlation between the incidence rate of cases during the study period and SAR estimates was 0.37 (95% CI, 0.24-0.49). We found that doubling the incidence rate of cases during the study period was associated with a 1.2% (95% CI, 0.5%-1.8%) higher household SAR. Conclusions Our findings suggest that the incidence rate of cases during the study period is associated with higher SAR. Ignoring this factor may overestimate SARs, especially for regions with high incidences, which further impacts control policies and epidemiological characterization of emerging variants.
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Affiliation(s)
- Can Wang
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Xiaotong Huang
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Eric H Y Lau
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China,Laboratory of Data Discovery for Health Limited, Hong Kong Science and Technology Park, New Territories, Hong Kong Special Administrative Region, China
| | - Benjamin J Cowling
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China,Laboratory of Data Discovery for Health Limited, Hong Kong Science and Technology Park, New Territories, Hong Kong Special Administrative Region, China
| | - Tim K Tsang
- Correspondence: Tim K. Tsang, PhD, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 7 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China ()
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Abstract
Since May 2022, a large number of monkeypox cases have been reported in Europe, the United States, and other nonendemic settings. Taking into account the strict measures implemented due to the coronavirus disease 2019 pandemic and the desire of people to reclaim what is perceived as lost time, mass gatherings this summer were highly attended. Based on data for the secondary attack rate among unvaccinated contacts from endemic countries, we estimate that, on average, >1 secondary case is anticipated per infectious person if he/she has a high number of group contacts (>30) or >8 close contacts. Although the role of group contacts in mass gatherings is uncertain (less likely to involve physical contact, shorter duration), close contacts associated with the event (eg, intimate/sexual contact with other attendees) might be the amplifying event. Enforcing awareness, early recognition, and engaging affected populations in the monkeypox response are important to control transmission.
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Affiliation(s)
- Vana Sypsa
- Correspondence: Vana Sypsa, PhD, Department of Hygiene, Epidemiology and Medical Statistics, Medical School, M. Asias 75 11527, Athens, Greece ()
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9
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Frutos AM, Kuan G, Lopez R, Ojeda S, Shotwell A, Sanchez N, Saborio S, Plazaola M, Barilla C, Kenah E, Balmaseda A, Gordon A. Infection-induced immunity is associated with protection against SARS-CoV-2 infection, but not decreased infectivity during household transmission. medRxiv 2022:2022. [PMID: 36263069 DOI: 10.1101/2022.10.10.22280915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Background Understanding the impact of infection-induced immunity on SARS-CoV-2 transmission will provide insight into the transition of SARS-CoV-2 to endemicity. Here we estimate the effects of prior infection induced immunity and children on SARS-CoV-2 transmission in households. Methods We conducted a household cohort study between March 2020-June 2022 in Managua, Nicaragua where when one household member tests positive for SARS-CoV-2, household members are closely monitored for SARS-CoV-2 infection. Using a pairwise survival model, we estimate the association of infection period, age, symptoms, and infection-induced immunity with secondary attack risk. Results Overall transmission occurred in 72.4% of households, 42% of household contacts were infected and the secondary attack risk was 13.0% (95% CI: 11.7, 14.6). Prior immunity did not impact the probability of transmitting SARS-CoV-2. However, participants with pre-existing infection-induced immunity were half as likely to be infected compared to naïve individuals (RR 0.53, 95% CI: 0.39, 0.72), but this reduction was not observed in children. Likewise, symptomatic infected individuals were more likely to transmit (RR 24.4, 95% CI: 7.8, 76.1); however, symptom presentation was not associated with infectivity of young children. Young children were less likely to transmit SARS-CoV-2 than adults. During the omicron era, infection-induced immunity remained protective against infection. Conclusions Infection-induced immunity is associated with protection against infection for adults and adolescents. While young children are less infectious, prior infection and asymptomatic presentation did not reduce their infectivity as was seen in adults. As SARS-CoV-2 transitions to endemicity, children may become more important in transmission dynamics. Article summary Infection-induced immunity protects against SARS-CoV-2 infection for adolescents and adults; however, there was no protection in children. Prior immunity in an infected individual did not impact the probability they will spread SARS-CoV-2 in a household setting.
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10
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López-Muñoz I, Torrella A, Pérez-Quílez O, Castillo-Zuza A, Martró E, Bordoy AE, Saludes V, Blanco I, Soldevila L, Estrada O, Valerio L, Roure S, Vallès X. SARS-CoV-2 Secondary Attack Rates in Vaccinated and Unvaccinated Household Contacts during Replacement of Delta with Omicron Variant, Spain. Emerg Infect Dis 2022; 28:1999-2008. [PMID: 36037811 PMCID: PMC9514368 DOI: 10.3201/eid2810.220494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We performed a prospective, cross-sectional study of household contacts of symptomatic index case-patients with SARS-CoV-2 infection during the shift from Delta- to Omicron-dominant variants in Spain. We included 466 household contacts from 227 index cases. The secondary attack rate was 58.2% (95% CI 49.1%-62.6%) during the Delta-dominant period and 80.9% (95% CI 75.0%-86.9%) during the Omicron-dominant period. During the Delta-dominant period, unvaccinated contacts had higher probability of infection than vaccinated contacts (odds ratio 5.42, 95% CI 1.6-18.6), but this effect disappeared at ≈20 weeks after vaccination. Contacts showed a higher relative risk of infection (9.16, 95% CI 3.4-25.0) in the Omicron-dominant than Delta-dominant period when vaccinated within the previous 20 weeks. Our data suggest vaccine evasion might be a cause of rapid spread of the Omicron variant. We recommend a focus on developing vaccines with long-lasting protection against severe disease, rather than only against infectivity.
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11
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Krieg SJ, Schnur JJ, Miranda ML, Pfrender ME, Chawla NV. Symptomatic, Presymptomatic, and Asymptomatic Transmission of SARS-CoV-2 in a University Student Population, August-November 2020. Public Health Rep 2022; 137:1023-1030. [PMID: 35848117 PMCID: PMC9358125 DOI: 10.1177/00333549221110300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVES The impact and risk of SARS-CoV-2 transmission from asymptomatic and presymptomatic hosts remains an open question. This study measured the secondary attack rates (SARs) and relative risk (RR) of SARS-CoV-2 transmission from asymptomatic and presymptomatic index cases as compared with symptomatic index cases. METHODS We used COVID-19 test results, daily health check reports, and contact tracing data to measure SARs and corresponding RRs among close contacts of index cases in a cohort of 12 960 young adults at the University of Notre Dame in Indiana for 103 days, from August 10 to November 20, 2020. Further analysis included Fisher exact tests to determine the association between symptoms and COVID-19 infection and z tests to determine statistical differences between SARs. RESULTS Asymptomatic rates of transmission of SARS-CoV-2 were higher (SAR = 0.19; 95% CI, 0.14-0.24) than was estimated in prior studies, producing an RR of 0.75 (95% CI, 0.54-1.07) when compared with symptomatic transmission. In addition, the transmission rate associated with presymptomatic cases (SAR = 0.25; 95% CI, 0.21-0.30) was approximately the same as that for symptomatic cases (SAR = 0.25; 95% CI, 0.19-0.31). Furthermore, different symptoms were associated with different transmission rates. CONCLUSIONS Asymptomatic and presymptomatic hosts of SARS-CoV-2 are a risk for community spread of COVID-19, especially with new variants emerging. Moreover, typical symptom checks may easily miss people who are asymptomatic or presymptomatic but still infectious. Our study results may be used as a guide to analyze the spread of SARS-CoV-2 variants and help inform appropriate public health measures as they relate to asymptomatic and presymptomatic cases.
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Affiliation(s)
- Steven J. Krieg
- Lucy Family Institute for Data and
Society, University of Notre Dame, Notre Dame, IN, USA
| | - Jennifer J. Schnur
- Lucy Family Institute for Data and
Society, University of Notre Dame, Notre Dame, IN, USA
| | - Marie Lynn Miranda
- Lucy Family Institute for Data and
Society, University of Notre Dame, Notre Dame, IN, USA
| | - Michael E. Pfrender
- Lucy Family Institute for Data and
Society, University of Notre Dame, Notre Dame, IN, USA
| | - Nitesh V. Chawla
- Lucy Family Institute for Data and
Society, University of Notre Dame, Notre Dame, IN, USA
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12
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Cerami C, Popkin-Hall ZR, Rapp T, Tompkins K, Zhang H, Muller MS, Basham C, Whittelsey M, Chhetri SB, Smith J, Litel C, Lin KD, Churiwal M, Khan S, Rubinstein R, Claman F, Mollan K, Wohl D, Premkumar L, Powers KA, Juliano JJ, Lin FC, Lin JT. Household Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 in the United States: Living Density, Viral Load, and Disproportionate Impact on Communities of Color. Clin Infect Dis 2022; 74:1776-1785. [PMID: 34383889 PMCID: PMC8436395 DOI: 10.1093/cid/ciab701] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Households are hot spots for severe acute respiratory syndrome coronavirus 2 transmission. METHODS This prospective study enrolled 100 coronavirus disease 2019 (COVID-19) cases and 208 of their household members in North Carolina though October 2020, including 44% who identified as Hispanic or non-White. Households were enrolled a median of 6 days from symptom onset in the index case. Incident secondary cases within the household were detected using quantitative polymerase chain reaction of weekly nasal swabs (days 7, 14, 21) or by seroconversion at day 28. RESULTS Excluding 73 household contacts who were PCR-positive at baseline, the secondary attack rate (SAR) among household contacts was 32% (33 of 103; 95% confidence interval [CI], 22%-44%). The majority of cases occurred by day 7, with later cases confirmed as household-acquired by viral sequencing. Infected persons in the same household had similar nasopharyngeal viral loads (intraclass correlation coefficient = 0.45; 95% CI, .23-.62). Households with secondary transmission had index cases with a median viral load that was 1.4 log10 higher than those without transmission (P = .03), as well as higher living density (more than 3 persons occupying fewer than 6 rooms; odds ratio, 3.3; 95% CI, 1.02-10.9). Minority households were more likely to experience high living density and had a higher risk of incident infection than did White households (SAR, 51% vs 19%; P = .01). CONCLUSIONS Household crowding in the context of high-inoculum infections may amplify the spread of COVID-19, potentially contributing to disproportionate impact on communities of color.
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Affiliation(s)
- Carla Cerami
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Zachary R Popkin-Hall
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Tyler Rapp
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Kathleen Tompkins
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Haoming Zhang
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Meredith S Muller
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Christopher Basham
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Maureen Whittelsey
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Srijana B Chhetri
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Judy Smith
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Christy Litel
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Kelly D Lin
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Mehal Churiwal
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Salman Khan
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Rebecca Rubinstein
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Faith Claman
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Katie Mollan
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - David Wohl
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Lakshmanane Premkumar
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Kimberly A Powers
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jonathan J Juliano
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Feng-Chang Lin
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jessica T Lin
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
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Del Águila-Mejía J, Wallmann R, Calvo-Montes J, Rodríguez-Lozano J, Valle-Madrazo T, Aginagalde-Llorente A. Secondary Attack Rate, Transmission and Incubation Periods, and Serial Interval of SARS-CoV-2 Omicron Variant, Spain. Emerg Infect Dis 2022; 28:1224-1228. [PMID: 35393009 PMCID: PMC9155885 DOI: 10.3201/eid2806.220158] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Contact tracing data of SARS-CoV-2 Omicron variant cases during December 2021 in Cantabria, Spain, showed increased transmission (secondary attack rate 39%) compared with Delta cases (secondary attack rate 26%), uninfluenced by vaccination status. Incubation and serial interval periods were also reduced. Half of Omicron transmissions happened before symptom onset in the index case-patient.
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Ogata T, Tanaka H, Nozawa Y, Mukouyama K, Tanaka E, Osaki N, Noguchi E, Seo K, Wada K. Increased Secondary Attack Rate among Unvaccinated Household Contacts of Coronavirus Disease 2019 Patients with Delta Variant in Japan. Int J Environ Res Public Health 2022; 19:ijerph19073889. [PMID: 35409572 PMCID: PMC8997792 DOI: 10.3390/ijerph19073889] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/15/2022] [Accepted: 03/21/2022] [Indexed: 02/06/2023]
Abstract
This study aimed to elucidate the household secondary attack rate (HSAR) of the Delta variant in comparison to the Alpha variant, and evaluate the risk factors among unvaccinated household contacts of patients with coronavirus disease 2019 (COVID-19). We studied household contacts of index cases of COVID-19 infected with Delta (L452R mutation), Alpha (N501Y mutation), and wild strain from December 2020 through November 2021 in Itako, Japan. The HSARs of the entire household contact, and the contact of index case with Delta variant were calculated and compared across the risk factors. We used a generalized estimating equation regression model for the multivariate analysis. We enrolled 1257 unvaccinated contacts from 580 households. The HSAR was higher in household contacts of index patients with Delta (48.5%) than with Alpha variant (21.7%) (aOR = 3.34, p = 0.000). In Delta variants, the HSAR was higher in household contacts with spousal relationships to index patients (63.4%) than contacts with other relationships (45.5%) (aOR 1.94, p = 0.026), and was lower in household contacts of index patients aged ≤19 (33.1%) than for contacts of index cases aged 20–59 years (52.6%) (aOR = 0.50, p = 0.027). The result of our study can be used to devise informed strategy to prevent transmission within households.
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Affiliation(s)
- Tsuyoshi Ogata
- Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan; (Y.N.); (K.M.); (E.T.); (N.O.); (E.N.); (K.S.)
- Correspondence:
| | - Hideo Tanaka
- Fujiidera Public Health Center of Osaka Prefectural Government, Fujiidera 583-0024, Japan;
| | - Yumiko Nozawa
- Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan; (Y.N.); (K.M.); (E.T.); (N.O.); (E.N.); (K.S.)
| | - Kazue Mukouyama
- Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan; (Y.N.); (K.M.); (E.T.); (N.O.); (E.N.); (K.S.)
| | - Emiko Tanaka
- Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan; (Y.N.); (K.M.); (E.T.); (N.O.); (E.N.); (K.S.)
| | - Natsumi Osaki
- Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan; (Y.N.); (K.M.); (E.T.); (N.O.); (E.N.); (K.S.)
| | - Etsuko Noguchi
- Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan; (Y.N.); (K.M.); (E.T.); (N.O.); (E.N.); (K.S.)
| | - Kayoko Seo
- Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan; (Y.N.); (K.M.); (E.T.); (N.O.); (E.N.); (K.S.)
| | - Koji Wada
- Department of Public Health, Faculty of Medicine and Graduate School of Public Health, International University of Health and Welfare, Tokyo 107-8402, Japan;
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Meena MS, Priya S, Thirukumaran R, Gowrilakshmi M, Essakiraja K, Madhumitha MS. Factors influencing the acquisition of COVID infection among high-risk contacts of COVID-19 patients in Madurai district-A case control study. J Family Med Prim Care 2022; 11:182-189. [PMID: 35309654 PMCID: PMC8930103 DOI: 10.4103/jfmpc.jfmpc_355_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 07/12/2021] [Accepted: 09/24/2021] [Indexed: 12/24/2022] Open
Abstract
Introduction COVID is a new disease; understanding the transmission dynamics and epidemiological characteristics may help in developing the effective control measures. The study is done 1. To determine the various factors influencing the acquisition of COVID-19 infection among high-risk contacts 2. To estimate the secondary attack rate among high-risk contacts 3. To determine the factors in COVID index cases influencing their secondary attack rate. Methodology Unmatched case control study was conducted from March to August 2020 among 139 COVID index cases in Madurai district from March-May (Reference period) and their 50 COVID positive (cases), 551 COVID negative (controls) high-risk contacts. Case investigation form* and contact tracing Proforma*were used to collect data. Chi-square test and independent sample t test were used to find out the association. Univariate* and Multivariate logistic regression* were used to predict the risk of various factors in acquisition of COVID infection with the help of adjusted and unadjusted odds ratio. P value < 0.05 was considered statistically significant. Results Male contacts (P = 0.005, OR = 2.520), overcrowding (P = 0.007, OR = 3.810), and duration of exposure to index case (for 4-7 days P = 0.014, OR = 2.902, for >7 days P = 0.001, OR = 6.748 and for > 12 hours/day P = 0.000, OR = 5.543) were significant factors predicted to be associated with acquisition of COVID infection among high-risk contacts. Reproductive number (R0)* estimated was 1.3. Secondary attack rate (SAR)* estimated among high-risk contacts was 8.32%. Index cases whose outcome was death (P = 0.026); symptomatic index cases (P = 0.000), cases with fever (P = 0.001); sorethroat (P = 0.019); breathlessness (P = 0.010); cough (P = 0.006) and running nose (P = 0.002) had significantly higher mean SAR than their counterparts. Conclusion Contacts with above said risk factors who were found to be more prone to infection could be given special focus to prevent the transmission in them.
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Affiliation(s)
- M Selva Meena
- Assistant Professor, Institute of Community Medicine, Madurai Medical College, Madurai, Tamil Nadu, India
| | - S Priya
- Associate Professor, Institute of Community Medicine, Madurai Medical College, Madurai, Tamil Nadu, India
| | - R Thirukumaran
- Assistant Professor, Institute of Community Medicine, Madurai Medical College, Madurai, Tamil Nadu, India
| | - M Gowrilakshmi
- Postgraduates, Institute of Community Medicine, Madurai Medical College, Madurai, Tamil Nadu, India
| | - K Essakiraja
- Postgraduates, Institute of Community Medicine, Madurai Medical College, Madurai, Tamil Nadu, India
| | - M S Madhumitha
- Postgraduates, Institute of Community Medicine, Madurai Medical College, Madurai, Tamil Nadu, India
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16
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Baek YJ, Chung WS, Lee KH, Lee EH, Lee SJ, Kim J, Kim JH, Ahn JY, Jeong SJ, Choi JY, Yeom JS. Surveillance of Close Contacts and Implications of Pediatric Patients with COVID-19-Experiences from a Single Residential Treatment Center. Yonsei Med J 2022; 63:292-295. [PMID: 35184432 PMCID: PMC8860931 DOI: 10.3349/ymj.2022.63.3.292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/05/2022] [Accepted: 01/13/2022] [Indexed: 11/27/2022] Open
Abstract
Residential treatment centers (RTCs) are successful in isolating and closely monitoring adults confirmed with coronavirus disease 2019 (COVID-19), but there are concerns for children who need care. This study was conducted as a retrospective analysis of the surveillance of guardians who entered an RTC with infected pediatric patients to identify the secondary attack rate of COVID-19 to close contacts in a single RTC and to provide directions for developing guidelines for caregivers who co-isolate with infected children. When caregivers were admitted to this RTC, aside from negative confirmation before discharge, tests were additionally performed one or two times. There were 57 index children and adolescent patients who entered the RTC with their parents as caregivers. The secondary attack rate by pediatric patients to close contacts outside their households was 25% (95% confidence interval, 10.0 to 40.0) (8 out of 32 contacts). The transmissibility of SARS-CoV-2 in children was close to zero at 6 days after the confirmation tests. It is reasonable to test the close contacts of pediatric patients after 7 days of isolation to identify infections among caregivers.
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Affiliation(s)
- Yae Jee Baek
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Won Suk Chung
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Ki Hyun Lee
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Eun Hwa Lee
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Se Ju Lee
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jinnam Kim
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jung Ho Kim
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jin Young Ahn
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Su Jin Jeong
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jun Yong Choi
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Joon-Sup Yeom
- Division of Infectious Disease, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
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Yuan H, Reynolds C, Ng S, Yang W. Factors affecting the transmission of SARS-CoV-2 in school settings. Influenza Other Respir Viruses 2022; 16:643-652. [PMID: 35146922 PMCID: PMC9111692 DOI: 10.1111/irv.12968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/13/2022] [Accepted: 01/18/2022] [Indexed: 11/29/2022] Open
Abstract
Background Several studies have reported SARS‐CoV‐2 outbreaks in schools, with a wide range of secondary attack rate (SAR; range: 0–100%). We aimed to examine key risk factors to better understand SARS‐CoV‐2 transmission in schools. Methods We collected records of 35 SARS‐CoV‐2 school outbreaks globally published from January 2020 to July 2021 and compiled information on hypothesized risk factors. We utilized the directed acyclic graph (DAG) to conceptualize risk mechanisms, used logistic regression to examine each risk‐factor group, and further built multirisk models. Results The best‐fit model showed that the intensity of community transmission (adjusted odds ratio [aOR]: 1.11, 95% CI: 1.06–1.16, for each increase of 1 case per 10 000 persons per week) and individualism (aOR: 2.72, 95% CI: 1.50–4.95, above vs. below the mean) was associated higher risk, whereas preventive measures (aOR: 0.25, 95% CI: 0.19–0.32, distancing and masking vs. none) and higher population immunity (aOR: 0.57, 95% CI: 0.46–0.71) were associated with lower risk of SARS‐CoV‐2 transmission in schools. Compared with students in high schools, the aOR was 0.47 (95% CI: 0.23–0.95) for students in preschools and 0.90 (95% CI: 0.76–1.08) for students in primary schools. Conclusions Preventive measures in schools (e.g., social distancing and mask wearing) and communal efforts to lower transmission and increase vaccination uptake (i.e., vaccine‐induced population immunity) in the community should be taken to collectively reduce transmission and protect children in schools.
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Affiliation(s)
- Haokun Yuan
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Connor Reynolds
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Sydney Ng
- Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Wan Yang
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA
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18
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Martínez-Baz I, Trobajo-Sanmartín C, Burgui C, Casado I, Castilla J. Transmission of SARS-CoV-2 infection and risk factors in a cohort of close contacts. Postgrad Med 2022; 134:230-238. [PMID: 35102793 DOI: 10.1080/00325481.2022.2037360] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
PURPOSE Many factors might affect SARS-CoV-2 transmission, but their relevance is not well established. The objectives were to assess the secondary attack rate (SAR) and the risk factors for SARS-CoV-2 transmission from confirmed index cases to their close contacts in household and non-household settings. METHODS This cohort study included the close contacts of SARS-CoV-2 infected cases confirmed between May and December 2020 in Navarre, Spain. Epidemiological and clinical variables of the index case and close contacts were collected. The SAR was calculated, and the independent effect of each variable on the transmission risk was evaluated by logistic regression. RESULTS A total of 59,900 close contacts of 20,048 index cases were studied, and 53.6% were household contacts. SAR was 34.9% overall, 46.8% in household contacts and 21.1% in non-household contacts. The risk of transmission was higher in household setting (adjusted odds ratio (aOR) 2.96, 95% CI 2.84-3.07), from symptomatic index cases (aOR 1.50, 95% CI 1.43-1.58), immigrants (aOR 1.44, 95% CI 1.36-1.52), and increased with age. A higher susceptibility of close contacts was associated with 5-14 years of age, immigrants (aOR 1.54), very low or low-income level (aOR 1.27, and aOR, 1.17, respectively), healthcare work (aOR 1.21), and diagnosis of diabetes (aOR 1.14, 95%CI 1.03-1.25), chronic kidney disease (aOR 1.18, 95%CI 1.04-1.35), hypertension (aOR 1.11, 95% CI 1.03-1.19), and severe obesity (aOR 1.18, 95% CI 1.00-1.38). Transmission increased progressively from May to September 2020 as the B.1.177 variant became dominant. CONCLUSION The risk of SARS-CoV-2 infection was considerable among close contacts of infected persons. The higher risk associated with household contacts, immigrants, older index cases, close contacts with lower income level and comorbidities should be considered to address preventive interventions.
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Affiliation(s)
- Iván Martínez-Baz
- Instituto de Salud Pública de Navarra, Pamplona, Spain.,Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.,CIBER Epidemiología y Salud Pública (CIBERESP), Pamplona, Spain
| | - Camino Trobajo-Sanmartín
- Instituto de Salud Pública de Navarra, Pamplona, Spain.,Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.,CIBER Epidemiología y Salud Pública (CIBERESP), Pamplona, Spain
| | - Cristina Burgui
- Instituto de Salud Pública de Navarra, Pamplona, Spain.,Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.,CIBER Epidemiología y Salud Pública (CIBERESP), Pamplona, Spain
| | - Itziar Casado
- Instituto de Salud Pública de Navarra, Pamplona, Spain.,Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.,CIBER Epidemiología y Salud Pública (CIBERESP), Pamplona, Spain
| | - Jesús Castilla
- Instituto de Salud Pública de Navarra, Pamplona, Spain.,Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.,CIBER Epidemiología y Salud Pública (CIBERESP), Pamplona, Spain
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19
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Reukers DFM, van Boven M, Meijer A, Rots N, Reusken C, Roof I, van Gageldonk-Lafeber AB, van der Hoek W, van den Hof S. High Infection Secondary Attack Rates of Severe Acute Respiratory Syndrome Coronavirus 2 in Dutch Households Revealed by Dense Sampling. Clin Infect Dis 2022; 74:52-58. [PMID: 33822007 PMCID: PMC8083540 DOI: 10.1093/cid/ciab237] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Indoor environments are considered one of the main settings for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Households in particular represent a close-contact environment with high probability of transmission between persons of different ages and roles in society. METHODS Households with a laboratory-confirmed SARS-CoV-2 positive case in the Netherlands (March-May 2020) were included. At least 3 home visits were performed during 4-6 weeks of follow-up, collecting naso- and oropharyngeal swabs, oral fluid, feces and blood samples from all household members for molecular and serological analyses. Symptoms were recorded from 2 weeks before the first visit through to the final visit. Infection secondary attack rates (SAR) were estimated with logistic regression. A transmission model was used to assess household transmission routes. RESULTS A total of 55 households with 187 household contacts were included. In 17 households no transmission took place; in 11 households all persons were infected. Estimated infection SARs were high, ranging from 35% (95% confidence interval [CI], 24%-46%) in children to 51% (95% CI, 39%-63%) in adults. Estimated transmission rates in the household were high, with reduced susceptibility of children compared with adolescents and adults (0.67; 95% CI, .40-1.1). CONCLUSION Estimated infection SARs were higher than reported in earlier household studies, presumably owing to our dense sampling protocol. Children were shown to be less susceptible than adults, but the estimated infection SAR in children was still high. Our results reinforce the role of households as one of the main multipliers of SARS-CoV-2 infection in the population.
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Affiliation(s)
- Daphne F M Reukers
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | - Michiel van Boven
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | - Adam Meijer
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | - Nynke Rots
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | - Chantal Reusken
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | - Inge Roof
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | | | - Wim van der Hoek
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
| | - Susan van den Hof
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
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Abstract
In September of 2020, the Iowa Department of Public Health released guidance stating that persons exposed to someone with coronavirus disease (COVID-19) need not quarantine if the case-patient and the contact wore face masks at the time of exposure. This guidance differed from that issued by the Centers for Disease Control and Prevention. To determine the best action, we matched exposure information from COVID-19 case investigations with reported test results and calculated the secondary attack rates (SARs) after masked and unmasked exposures. Mask use by both parties reduced the SAR by half, from 25.6% to 12.5%. Longer exposure duration significantly increased SARs. Masks significantly reduced virus transmission when worn by both the case-patient and the contact, but SARs for each group were higher than anticipated. This finding suggests that quarantine after COVID-19 exposure is beneficial even if parties wore masks.
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Remón-Berrade M, Guillen-Aguinaga S, Sarrate-Adot I, Garcia-Garcia MP, Lerga-Berruezo MDC, Guillen-Aguinaga L, Guillen-Grima F. Risk of Secondary Household Transmission of COVID-19 from Health Care Workers in a Hospital in Spain. Epidemiologia (Basel) 2021; 3:1-10. [PMID: 36417263 PMCID: PMC9620916 DOI: 10.3390/epidemiologia3010001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND Hospital health care workers are at high risk of developing COVID-19 and transmitting the disease to their family upon returning home; the aim here is to estimate the secondary attack rate of COVID-19 in household contacts of health care workers and their transmission risk factors. MATERIAL AND METHODS COVID-19 cases in the health care workers of an academic hospital in Pamplona, Spain, from 2 March to 26 May 2020, were followed up. The secondary attack rate (SAR) was estimated from cases in household contacts of index cases and their risk factors by Poisson regression. RESULTS 89 index cases were studied from 99 notified cases in health care workers (89.0%), excluding secondary cases or those who lived alone. Forty-six secondary cases confirmed by the laboratory were found among 326 household contacts, a secondary attack rate of 14.11% (95% CI 10.75-18.31), and 33 household contacts with acute infection symptoms without microbiologic confirmation 10.12% (95% CI 7.30-13.87). Considering all the cases, the secondary attack rate was 27.3 (95% CI 22.75-32.38). Risk factors were the gender and profession of the index case, the number of people living in the household, and the number of persons per bedroom. When the index case health worker used a single room, it had a protective effect, with an incidence rate ratio (IRR) of 0.493 (95% CI 0.246-0.985); Conclusions: The secondary attack rate found among household contacts of health care workers is high. The preventive isolation of health care workers in individual rooms in their house may reduce the transmission in their families.
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Affiliation(s)
- Miren Remón-Berrade
- Department of Preventive Medicine, Clínica Universidad de Navarra, 31008 Pamplona, Navarra, Spain; (M.R.-B.); (I.S.-A.); (M.P.G.-G.); (M.d.C.L.-B.)
| | - Sara Guillen-Aguinaga
- Azpilagaña Health Center, Navarra Health Service, 31006 Pamplona, Navarra, Spain;
- Department of Health Sciences, Public University of Navarra (UPNA), 31008 Pamplona, Navarra, Spain
| | - Isabel Sarrate-Adot
- Department of Preventive Medicine, Clínica Universidad de Navarra, 31008 Pamplona, Navarra, Spain; (M.R.-B.); (I.S.-A.); (M.P.G.-G.); (M.d.C.L.-B.)
| | - Maria Pilar Garcia-Garcia
- Department of Preventive Medicine, Clínica Universidad de Navarra, 31008 Pamplona, Navarra, Spain; (M.R.-B.); (I.S.-A.); (M.P.G.-G.); (M.d.C.L.-B.)
| | - Maria del Carmen Lerga-Berruezo
- Department of Preventive Medicine, Clínica Universidad de Navarra, 31008 Pamplona, Navarra, Spain; (M.R.-B.); (I.S.-A.); (M.P.G.-G.); (M.d.C.L.-B.)
| | | | - Francisco Guillen-Grima
- Department of Preventive Medicine, Clínica Universidad de Navarra, 31008 Pamplona, Navarra, Spain; (M.R.-B.); (I.S.-A.); (M.P.G.-G.); (M.d.C.L.-B.)
- Department of Health Sciences, Public University of Navarra (UPNA), 31008 Pamplona, Navarra, Spain
- Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Navarra, Spain
- Correspondence: ; Tel.: +34-948-296-384
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Julin CH, Robertson AH, Hungnes O, Tunheim G, Bekkevold T, Laake I, Aune IF, Killengreen MF, Strand TR, Rykkvin R, Dorenberg DH, Stene-Johansen K, Berg ES, Bodin JE, Oftung F, Steens A, Næss LM. Household Transmission of SARS-CoV-2: A Prospective Longitudinal Study Showing Higher Viral Load and Increased Transmissibility of the Alpha Variant Compared to Previous Strains. Microorganisms 2021; 9:2371. [PMID: 34835495 PMCID: PMC8622435 DOI: 10.3390/microorganisms9112371] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 11/08/2021] [Accepted: 11/11/2021] [Indexed: 11/23/2022] Open
Abstract
We studied the secondary attack rate (SAR), risk factors, and precautionary practices of household transmission in a prospective, longitudinal study. We further compared transmission between the Alpha (B.1.1.7) variant and non-Variant of Concern (non-VOC) viruses. From May 2020 throughout April 2021, we recruited 70 confirmed COVID-19 cases with 146 household contacts. Participants donated biological samples eight times over 6 weeks and answered questionnaires. SARS-CoV-2 infection was detected by real-time RT-PCR. Whole genome sequencing and droplet digital PCR were used to establish virus variant and viral load. SARS-CoV-2 transmission occurred in 60% of the households, and the overall SAR for household contacts was 50%. The SAR was significantly higher for the Alpha variant (78%) compared with non-VOC viruses (43%) and was associated with a higher viral load. SAR was higher in household contacts aged ≥40 years (69%) than in younger contacts (40-47%), and for contacts of primary cases with loss of taste/smell. Children had lower viral loads and were more often asymptomatic than adults. Sleeping separately from the primary case reduced the risk of transmission. In conclusion, we found substantial household transmission, particularly for the Alpha variant. Precautionary practices seem to reduce SAR, but preventing household transmission may become difficult with more contagious variants, depending on vaccine use and effectiveness.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Lisbeth Meyer Næss
- Division of Infection Control, Norwegian Institute of Public Health, P.O. Box 222 Skøyen, 0213 Oslo, Norway; (C.H.J.); (A.H.R.); (O.H.); (G.T.); (T.B.); (I.L.); (I.F.A.); (M.F.K.); (T.R.S.); (R.R.); (D.H.D.); (K.S.-J.); (E.S.B.); (J.E.B.); (F.O.); (A.S.)
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Bistaraki A, Roussos S, Tsiodras S, Sypsa V. Age-dependent effects on infectivity and susceptibility to SARS-CoV-2 infection: results from nationwide contact tracing data in Greece. Infect Dis (Lond) 2021; 54:186-195. [PMID: 34743646 DOI: 10.1080/23744235.2021.1995627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Understanding the factors that affect the transmissibility of SARS-CoV-2 remains important to keep transmission low and maximize the health benefits of vaccination. We assessed the factors associated with the transmissibility of SARS-CoV-2 based on contact tracing data. METHODS From 1 October to 9 December 2020, 29,385 laboratory-confirmed SARS-CoV-2 cases (index cases, i.e. the first identified laboratory-confirmed cases or with the earliest symptom onset in a setting) and 64,608 traced contacts were identified in Greece. We assessed the prevalence of symptoms in cases, calculated secondary attack rates and assessed factors associated with infectivity and susceptibility to infection. RESULTS There were 11,232 contacts secondarily infected (secondary attack rate: 17.4%, 95% CI:17.0-17.8). Contacts aged 0-11 and 12-17 years were less susceptible to infection than adults 65 years or older (odds ratio (OR) [95% CI]: 0.28 [0.26-0.32] and 0.44 [0.40-0.49], respectively). Index cases aged 65 years or older were more likely to infect their contacts than other adults or children/adolescents. The odds of infection [95% CI] were higher in contacts exposed within the household (1.71 [1.59-1.85] vs. other) and in cases with cough (1.17 [1.11-1.25] vs. no cough). There was an interaction between the age of the index and the age of the contact with contacts 65 years or older having a higher probability of infection when exposed to cases of similar age than to children. CONCLUSIONS Our findings highlight the role of age and age mixing in infectivity and susceptibility to SARS-CoV-2 infection. Precautions are necessary for individuals 65 or older as they have higher infectivity and susceptibility in contact with their peers.
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Affiliation(s)
- Angeliki Bistaraki
- Department of Nursing, School of Health Sciences, Hellenic Mediterranean University, Crete, Greece
| | - Sotirios Roussos
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Sotirios Tsiodras
- 4th Department of Internal Medicine, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Vana Sypsa
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, Athens, Greece
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Lindstrøm JC, Engebretsen S, Kristoffersen AB, Rø GØI, Palomares ADL, Engø-Monsen K, Madslien EH, Forland F, Nygård KM, Hagen F, Gantzel G, Wiklund O, Frigessi A, de Blasio BF. Increased transmissibility of the alpha SARS-CoV-2 variant: evidence from contact tracing data in Oslo, January to February 2021. Infect Dis (Lond) 2021; 54:72-77. [PMID: 34618665 DOI: 10.1080/23744235.2021.1977382] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND Information about the contagiousness of new SARS-CoV-2 variants, including the alpha lineage, and how they spread in various locations is essential. Country-specific estimates are needed because local interventions influence transmissibility. METHODS We analysed contact tracing data from Oslo municipality, reported from January through February 2021, when the alpha lineage became predominant in Norway and estimated the relative transmissibility of the alpha lineage with the use of Poisson regression. RESULTS Within households, we found an increase in the secondary attack rate by 60% (95% CI 20-114%) among cases infected with the alpha lineage compared to other variants; including all close contacts, the relative increase in the secondary attack rate was 24% (95% CI -6%-43%). There was a significantly higher risk of infecting household members in index cases aged 40-59 years who were infected with the alpha lineage; we found no association between transmission and household size. Overall, including all close contacts, we found that the reproduction number among cases with the alpha lineage was increased by 24% (95% CI 0%-52%), corresponding to an absolute increase of 0.19, compared to the group of index cases infected with other variants. CONCLUSION Our study suggests that households are the primary locations for rapid transmission of the new lineage alpha.
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Affiliation(s)
| | | | - Anja Bråthen Kristoffersen
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Gunnar Øyvind Isaksson Rø
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Alfonso Diz-Lois Palomares
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | | | - Elisabeth Henie Madslien
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Frode Forland
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Karin Maria Nygård
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Frode Hagen
- Oslo Municipality Health Service, Oslo, Norway
| | | | | | - Arnoldo Frigessi
- Oslo Centre for Biostatistics and Epidemiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Oslo Centre for Biostatistics and Epidemiology, Oslo University Hospital, Oslo, Norway
| | - Birgitte Freiesleben de Blasio
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.,Oslo Centre for Biostatistics and Epidemiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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25
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Petersen MS, Kristiansen MF, Reinert HW, Fjallsbak JP, Christiansen DH, Gaini S, Steig BÁ, Møller LF, Strøm M, Weihe P. Seroprevalence of SARS-CoV-2-Specific Antibodies among Quarantined Close Contacts of COVID-19 Patients, Faroe Islands, 2020. Emerg Infect Dis 2021; 27:2795-2801. [PMID: 34437829 PMCID: PMC8544982 DOI: 10.3201/eid2711.204948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Close contacts of coronavirus disease (COVID-19) patients are at high risk for severe acute respiratory syndrome 2 (SARS-CoV-2) infection. We assessed the seroprevalence of SARS-CoV-2–specific antibodies among quarantined close contacts of COVID-19 patients in the Faroe Islands. We invited quarantined close contacts of COVID-19 index patients identified during March 3–April 22, 2020, to participate in this study; 584 (81%) contacts consented and underwent serologic testing. Among the 584 participants, 32 (5.5%) were seropositive for total antibody against SARS-CoV-2. Household and young or elderly contacts had higher risk for seropositivity than other contacts. We found a secondary attack rate of 19.2%. Seroprevalence among close contacts was almost 10-fold higher than among the general population of the Faroe Islands. Regularly testing household close contacts of COVID-19 patients might help track the transmission of SARS-CoV-2.
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26
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Ogata T, Irie F, Ogawa E, Ujiie S, Seki A, Wada K, Tanaka H. Secondary Attack Rate among Non-Spousal Household Contacts of Coronavirus Disease 2019 in Tsuchiura, Japan, August 2020-February 2021. Int J Environ Res Public Health 2021; 18:8921. [PMID: 34501511 DOI: 10.3390/ijerph18178921] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/22/2021] [Accepted: 08/23/2021] [Indexed: 12/24/2022]
Abstract
Household secondary attack rate (HSAR) by risk factor might have a higher transmission rate between spouses. We investigated risk factors for the HSAR among non-spousal household contacts of patients with coronavirus disease 2019 (COVID-19). We studied household contacts of index cases of COVID-19 in Tsuchiura, Japan, from August 2020 through February 2021. The HSARs of the whole household contacts and non-spousal household contacts were calculated and compared across risk factors. We used a generalized linear mixed regression model for multivariate analysis. We enrolled 496 household contacts of 236 index COVID-19 cases. The HSAR was higher for spousal household contacts (37.8%) than for other contacts (21.2%). The HSAR was lower for non-spousal household contacts with a household size (number of household members) of two (18.2%), compared to the HSAR for contacts with a household size ≥4. The HSAR was higher for non-spousal household contacts of index patients with ≥3 days of diagnostic delay (period between onset and diagnosis) (26.0%) compared to those with ≤2 days’ delay (12.5%) (p = 0.033). Among non-spousal household contacts, the HSAR was low for those with a household size of two and was high for contacts of index patients with a long diagnostic delay.
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27
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Thompson HA, Mousa A, Dighe A, Fu H, Arnedo-Pena A, Barrett P, Bellido-Blasco J, Bi Q, Caputi A, Chaw L, De Maria L, Hoffmann M, Mahapure K, Ng K, Raghuram J, Singh G, Soman B, Soriano V, Valent F, Vimercati L, Wee LE, Wong J, Ghani AC, Ferguson NM. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Setting-specific Transmission Rates: A Systematic Review and Meta-analysis. Clin Infect Dis 2021; 73:e754-e764. [PMID: 33560412 PMCID: PMC7929012 DOI: 10.1093/cid/ciab100] [Citation(s) in RCA: 115] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Understanding the drivers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission is crucial for control policies, but evidence of transmission rates in different settings remains limited. METHODS We conducted a systematic review to estimate secondary attack rates (SARs) and observed reproduction numbers (Robs) in different settings exploring differences by age, symptom status, and duration of exposure. To account for additional study heterogeneity, we employed a beta-binomial model to pool SARs across studies and a negative-binomial model to estimate Robs. RESULTS Households showed the highest transmission rates, with a pooled SAR of 21.1% (95% confidence interval [CI]:17.4-24.8). SARs were significantly higher where the duration of household exposure exceeded 5 days compared with exposure of ≤5 days. SARs related to contacts at social events with family and friends were higher than those for low-risk casual contacts (5.9% vs 1.2%). Estimates of SARs and Robs for asymptomatic index cases were approximately one-seventh, and for presymptomatic two-thirds of those for symptomatic index cases. We found some evidence for reduced transmission potential both from and to individuals younger than 20 years of age in the household context, which is more limited when examining all settings. CONCLUSIONS Our results suggest that exposure in settings with familiar contacts increases SARS-CoV-2 transmission potential. Additionally, the differences observed in transmissibility by index case symptom status and duration of exposure have important implications for control strategies, such as contact tracing, testing, and rapid isolation of cases. There were limited data to explore transmission patterns in workplaces, schools, and care homes, highlighting the need for further research in such settings.
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Affiliation(s)
- Hayley A Thompson
- MRC Centre for Global Infectious Disease Analysis & World Health Organization Collaborating Centre for Infectious Disease Modelling, Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK
| | - Andria Mousa
- MRC Centre for Global Infectious Disease Analysis & World Health Organization Collaborating Centre for Infectious Disease Modelling, Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK
| | - Amy Dighe
- MRC Centre for Global Infectious Disease Analysis & World Health Organization Collaborating Centre for Infectious Disease Modelling, Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK
| | - Han Fu
- MRC Centre for Global Infectious Disease Analysis & World Health Organization Collaborating Centre for Infectious Disease Modelling, Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK
| | - Alberto Arnedo-Pena
- Sección de Epidemiología, Centro de Salud Pública de Castellón, Valencia, Spain
- Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Valencia, Spain
| | - Peter Barrett
- School of Public Health, University College Cork, Cork, Ireland
- Irish Centre for Maternal and Child Health Research (INFANT), University College Cork, Cork, Ireland
| | - Juan Bellido-Blasco
- Sección de Epidemiología, Centro de Salud Pública de Castellón, Valencia, Spain
- Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Valencia, Spain
- Facultad de Ciencias de la Salud, Universitat Jaime I (UJI), Castelló, Spain
| | - Qifang Bi
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Antonio Caputi
- Interdisciplinary Department of Medicine, University of Bari, Unit of Occupational Medicine, University Hospital of Bari, Bari, Italy
| | - Liling Chaw
- PAPRSB Institute of Health Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, Brunei
| | - Luigi De Maria
- Interdisciplinary Department of Medicine, University of Bari, Unit of Occupational Medicine, University Hospital of Bari, Bari, Italy
| | - Matthias Hoffmann
- Division of General Internal Medicine, Infectious Diseases and Hospital Epidemiology, Cantonal Hospital Olten, Olten, Switzerland
| | - Kiran Mahapure
- Department of Plastic Surgery, Dr Prabhakar Kore Hospital and MRC, Belgaum, Karnataka, India
| | | | | | - Gurpreet Singh
- Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
| | - Biju Soman
- Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
| | | | - Francesca Valent
- SOC Istituto di Igiene ed Epidemiologia Clinica, Azienda Sanitaria Universitaria Friuli Centrale, Udine, Italy
| | - Luigi Vimercati
- Interdisciplinary Department of Medicine, University of Bari, Unit of Occupational Medicine, University Hospital of Bari, Bari, Italy
| | - Liang En Wee
- Department of Infectious Diseases, Singapore General Hospital, Singapore, Singapore
| | - Justin Wong
- PAPRSB Institute of Health Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, Brunei
- Disease Control Division, Ministry of Health, Brunei
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis & World Health Organization Collaborating Centre for Infectious Disease Modelling, Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK
| | - Neil M Ferguson
- MRC Centre for Global Infectious Disease Analysis & World Health Organization Collaborating Centre for Infectious Disease Modelling, Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK
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Shah K, Kandre Y, Mavalankar D. Secondary attack rate in household contacts of COVID-19 Paediatric index cases: a study from Western India. J Public Health (Oxf) 2021; 43:243-245. [PMID: 33454742 PMCID: PMC7928715 DOI: 10.1093/pubmed/fdaa269] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 12/21/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Role of pediatric cases in secondary transmission of COVID-19 is not well understood. We aim to study secondary attack rate (SAR) of COVID-19 in household contacts of pediatric index cases from Gujarat, Western Indian state. METHODS For this cross-sectional study, details of 2412 paediatric patients were collected from Government records. Through stratified random sampling 10% (n = 242) of the patients were selected for the study and were telephonically contacted for obtaining the details of household secondary infection; 72 pediatric index cases having 287 household contacts were included in the study. RESULTS The SAR in household contacts of pediatric index cases was 1.7% (95% CI: 0.74-4%). Majority of the index cases were males (94.4%) with 66% of the patients being admitted at various hospitals and isolation facilities (45%); 37% were home quarantine. Of 72, 50 (74%) cases were aged between 12 and 18 years. The family size of the index cases causing secondary infection was comparatively larger than index cases without secondary household infection (6.75 ± 2.3 versus 4.9 ± 1.9; P = 0.034). CONCLUSIONS The household SAR from pediatric patients is low and is closely associated with the family size of the index cases. Hence, home quarantine should be advocated in smaller families with appropriate isolation facilities.
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Affiliation(s)
- Komal Shah
- Department of Public Health, Indian Institute of Public Health at Gandhinagar, Gandhinagar 382042, Gujarat, India
| | - Yogini Kandre
- Department of Public Health, Indian Institute of Public Health at Gandhinagar, Gandhinagar 382042, Gujarat, India
| | - Dileep Mavalankar
- Department of Public Health, Indian Institute of Public Health at Gandhinagar, Gandhinagar 382042, Gujarat, India
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Loenenbach A, Markus I, Lehfeld AS, An der Heiden M, Haas W, Kiegele M, Ponzi A, Unger-Goldinger B, Weidenauer C, Schlosser H, Beile A, Buchholz U. SARS-CoV-2 variant B.1.1.7 susceptibility and infectiousness of children and adults deduced from investigations of childcare centre outbreaks, Germany, 2021. ACTA ACUST UNITED AC 2021; 26. [PMID: 34047274 PMCID: PMC8161729 DOI: 10.2807/1560-7917.es.2021.26.21.2100433] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We investigated three SARS-CoV-2 variant B.1.1.7 childcare centre and related household outbreaks. Despite group cohorting, cases occurred in almost all groups, i.e. also among persons without close contact. Children’s secondary attack rates (SAR) were similar to adults (childcare centres: 23% vs 30%; p = 0.15; households: 32% vs 39%; p = 0.27); child- and adult-induced household outbreaks also led to similar SAR. With the advent of B.1.1.7, susceptibility and infectiousness of children and adults seem to converge. Public health measures should be revisited accordingly.
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Affiliation(s)
- Anna Loenenbach
- These authors contributed equally to this article and share first authorship.,Department for Infectious Disease Epidemiology, Robert Koch-Institute, Berlin, Germany
| | - Inessa Markus
- These authors contributed equally to this article and share first authorship.,Department for Infectious Disease Epidemiology, Robert Koch-Institute, Berlin, Germany
| | - Ann-Sophie Lehfeld
- Department for Infectious Disease Epidemiology, Robert Koch-Institute, Berlin, Germany
| | | | - Walter Haas
- Department for Infectious Disease Epidemiology, Robert Koch-Institute, Berlin, Germany
| | - Maya Kiegele
- Local Health Authority Bergstraße/Hesse, Heppenheim, Germany.,Federal Office of Administration, Cologne, Germany
| | - André Ponzi
- Local Health Authority Bergstraße/Hesse, Heppenheim, Germany.,Federal Office of Administration, Cologne, Germany
| | | | | | - Helen Schlosser
- Local Health Authority Bergstraße/Hesse, Heppenheim, Germany
| | - Alexander Beile
- Local Health Authority Bergstraße/Hesse, Heppenheim, Germany
| | - Udo Buchholz
- Department for Infectious Disease Epidemiology, Robert Koch-Institute, Berlin, Germany
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Aishwarya M, Singh M, Panda PK. Primary to tertiary COVID-19 transmission in a hospital - A cluster outbreak analysis. J Family Med Prim Care 2021; 10:1489-1492. [PMID: 34041199 PMCID: PMC8140238 DOI: 10.4103/jfmpc.jfmpc_2104_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/02/2020] [Accepted: 01/01/2021] [Indexed: 01/11/2023] Open
Abstract
The recent pandemic of SARS COV-2, a novel coronavirus requires research into understanding of its transmission dynamics and clinical presentations to help in understanding the spread of the disease, how to prevent it not only locally but also for national policy formulations. In this study, we described the transmission dynamics and clinical presentations of a cluster outbreak of SARS COV-2 in a tertiary level hospital. We also calculated the secondary attack rate for the primary, secondary, and tertiary transmissions. We conclude that symptomatic COVID-19 are primary and secondary contacts rather than tertiary contacts, hence, former to be quarantined. However, tertiary transmission is causing more COVID-19 compared to other transmissions in a hospital outbreak without further transmissibility. And overall secondary attack rate is very low in a hospital outbreak.
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Affiliation(s)
- M Aishwarya
- Department of Medicine (Infectious Disease Division), All India Institute of Medical Sciences (AIIMS), Rishikesh, Uttarakhand, India
| | - Mahendra Singh
- Department of Community and Family Medicine, All India Institute of Medical Sciences (AIIMS), Rishikesh, Uttarakhand, India
| | - Prasan K Panda
- Department of Medicine (Infectious Disease Division), All India Institute of Medical Sciences (AIIMS), Rishikesh, Uttarakhand, India
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Kuba Y, Shingaki A, Nidaira M, Kakita T, Maeshiro N, Oyama M, Kudeken T, Miyagi A, Yamauchi M, Kyan H. The characteristics of household transmission during COVID-19 outbreak in Okinawa, Japan from February to May 2020. Jpn J Infect Dis 2021; 74:579-583. [PMID: 33952770 DOI: 10.7883/yoken.jjid.2020.943] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
From February 14 to May 31, 2020, the Okinawa prefecture confirmed 142 cases of coronavirus disease (COVID-19). Among them, 78 were the first cases of a household, with 174 household contacts. Of the 174 contacts, 21 contracted infection, indicating a secondary attack rate of 12.1% (95% confidence interval (CI) 7.6-17.9%). No significant differences were observed in the demographics and quantitative reverse transcription polymerase chain reaction (qRT-PCR) test results between first cases who became the source of infection to the household members or not. The secondary attack rates per various characteristics of the household members were significantly different: aged > 69 years (40.9% [95% CI 20.7-63.6%]) and those with underlying diseases (36.0% [95% CI 18.0-57.5%]). When the period from the onset to the isolation of the first household case was within 3 days, the secondary attack rate was low (4.5% [95% CI 0.1-22.8%]). Among the 21 secondary cases, 11 (52.4%) developed within 5 days from symptom onset in the first case within the same household. This indicates that secondary infection within the household occurred immediately after symptom onset in the first case. Thus, isolation of a suspected patient is a solution to reduce secondary household infections.
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Affiliation(s)
- Yumani Kuba
- Okinawa Prefectural Institute of Health and Environment, Japan
| | - Ayako Shingaki
- Okinawa Prefectural Institute of Health and Environment, Japan
| | - Minoru Nidaira
- Okinawa Prefectural Institute of Health and Environment, Japan
| | - Tetsuya Kakita
- Okinawa Prefectural Institute of Health and Environment, Japan
| | | | - Minori Oyama
- Okinawa Prefectural Institute of Health and Environment, Japan
| | | | - Ayano Miyagi
- Okinawa Prefectural Institute of Health and Environment, Japan
| | - Miyuki Yamauchi
- Okinawa Prefectural Institute of Health and Environment, Japan
| | - Hisako Kyan
- Okinawa Prefectural Institute of Health and Environment, Japan
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Spielberger BD, Goerne T, Geweniger A, Henneke P, Elling R. Intra-Household and Close-Contact SARS-CoV-2 Transmission Among Children - a Systematic Review. Front Pediatr 2021; 9:613292. [PMID: 33898355 PMCID: PMC8062727 DOI: 10.3389/fped.2021.613292] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 02/01/2021] [Indexed: 01/19/2023] Open
Abstract
Introduction: The outbreak of the novel coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a range of emergency measures worldwide. Early in the pandemic, children were suspected to act as drivers of the COVID-19 spread in the population, which was based on experiences with influenza virus and other respiratory pathogens. Consequently, closures of schools and kindergartens were implemented in many countries around the world, alongside with other non-pharmaceutical interventions for transmission control. Given the grave and multifaceted consequences of contact restriction measures for children, it is crucial to better understand the effect size of these incisive actions for the COVID-19 pandemic. Therefore, we systematically review the current evidence on transmission of SARS-CoV-2 to and by children. Data Sources: PubMed and preprints uploaded on medRxiv. Study Selection: Original research articles, case reports, brief communications, and commentaries were included into the analysis. Each title or abstract was independently reviewed to identify relevant articles. Studies in other languages than English were not included. Data Extraction: Two reviewers independently reviewed the selected studies. Extracted data included citation of each study, type of healthcare setting, location of the study, characteristics of patient population, and reported outcomes. Results: Data on transmission of SARS-CoV-2 on or by children is scarce. Several studies show a lower seropositivity of children compared to adults, suggesting a lower susceptibility of especially younger children. Most insight currently comes from household studies suggesting, that children are predominantly infected by their household contacts. The contagiousness however, seems to be comparable between children and adults, based on our meta-analysis of included studies. Conclusions: Larger and systematic studies are urgently needed to better understand the age dependent patterns of SARS-CoV-2 transmission and thereby design more effective non-pharmaceutical interventions to reduce disease transmission.
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Affiliation(s)
- Benedikt D. Spielberger
- Center for Pediatrics and Adolescent Medicine, Medical Center-University of Freiburg, Freiburg, Germany
| | - Tessa Goerne
- Center for Pediatrics and Adolescent Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- Institute for Immunodeficiency, Center for Chronic Immunodeficiency, Medical Center – University of Freiburg, Freiburg, Germany
| | - Anne Geweniger
- Center for Pediatrics and Adolescent Medicine, Medical Center-University of Freiburg, Freiburg, Germany
| | - Philipp Henneke
- Center for Pediatrics and Adolescent Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- Institute for Immunodeficiency, Center for Chronic Immunodeficiency, Medical Center – University of Freiburg, Freiburg, Germany
| | - Roland Elling
- Center for Pediatrics and Adolescent Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- Institute for Immunodeficiency, Center for Chronic Immunodeficiency, Medical Center – University of Freiburg, Freiburg, Germany
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Tian T, Huo X. Secondary attack rates of COVID-19 in diverse contact settings, a meta-analysis. J Infect Dev Ctries 2020; 14:1361-1367. [PMID: 33378276 DOI: 10.3855/jidc.13256] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 11/17/2020] [Indexed: 10/31/2022] Open
Abstract
INTRODUCTION The secondary attack rate (SAR) measures the transmissibility of an infectious agent. The reported SAR of COVID-19 varied in a broad range, and between different contact settings. METHODOLOGY We conducted a meta-analysis on the SAR of COVID-19 with adherence to the PRISMA guideline. We searched published literatures and preprints in international databases of PubMed and medRxiv, and in five major Chinese databases as of 20 April 2020, using the following search terms: ("COVID-19" and "secondary attack rate") or ("COVID-19" and "close contact"). The random effect model was chosen for pooled analyses, using R (version 3.6.3). RESULTS A total of 1,136 references were retrieved and 18 of them remained after screening. The pooled SAR of COVID-19 was 0.07 (95%: 0.03-0.12) in general. It differed significantly between contact settings, peaking in households (0.20, 95%: 0.15-0.28), followed by in social gatherings (0.06, 95%: 0.03-0.10). The point estimates of the pooled SARs in health facilities, transports, and work/study settings were all as low as 0.01. Among all the secondary cases, the proportion of asymptomatic infections was estimated to be 0.17 (95% CI: 0.09 - 0.34). The proportion was higher in households (0.26, 95% CI: 0.12-0.56), than in other contact settings. CONCLUSIONS The transmission risk of SARS-CoV-2 is much higher in households than in other scenarios. Identification of asymptomatic secondary infections should be enhanced in households.
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Affiliation(s)
- Ting Tian
- Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
| | - Xiang Huo
- Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
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Abstract
Coronavirus disease 2019 (COVID-19) is a novel virus with continuously evolving transmission trends. Contact tracing and quarantining of positive cases are chief strategies of disease control that has been accepted globally, though scientific knowledge regarding household transmission of the COVID-19 through contact of positive case is sparse. Current systematic review was planned to assess global statistics and characteristics of household secondary attack rate (SAR) of COVID-19. Eligible articles were retrieved through search of-MEDLINE, SCOPUS and EMBASE for the period December 2019 to 15 June 2020. Search terms were developed to identify articles reporting household SARs in various countries. After initial screening of 326 articles, 13 eligible studies were included in the final evidence synthesis. We found that SAR varies widely across countries with lowest reported rate as 4.6% and highest as 49.56%. The rates were unaffected by confounders such as population of the country, lockdown status and geographic location. Review suggested greater vulnerability of spouse and elderly population for secondary transmission than other household members. It was also observed that quarantining and isolation are most effective strategies for prevention of the secondary transmission of the disease. Symptomatic status of the index case emerged to be a critical factor, with very low transmission probability during asymptomatic phase. Present review findings recommend that adequate measures should be provided to protect the vulnerable population as only case tracing and quarantining might be insufficient. It should be combined with advisory for limiting household contacts and active surveillance for symptom onset.
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Affiliation(s)
- Komal Shah
- Assistant Professor, Indian Institute of Public Health Gandhinagar, Gujarat, India
- Corresponding Author: Dr. Komal Shah, Assistant Professor, Indian Institute of Public Health - Gandhinagar, Opp. Air Force Head Quarters, Nr. Lekawada Bus Stop, Gandhinagar-Chiloda Road, Gandhinagar - 382042. Mob: 9924264500,
| | - Deepak Saxena
- Professor, Indian Institute of Public Health Gandhinagar, Gujarat, India
| | - Dileep Mavalankar
- Director, Indian Institute of Public Health Gandhinagar, Gujarat, India
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Bao C, Pan E, Ai J, Dai Q, Xu K, Shi N, Gao Q, Hu J, Peng Z, Huang H, Jin H, Zhu F. COVID-19 outbreak following a single patient exposure at an entertainment site: An epidemiological study. Transbound Emerg Dis 2020; 68:773-781. [PMID: 32725765 DOI: 10.1111/tbed.13742] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/29/2020] [Accepted: 07/15/2020] [Indexed: 01/12/2023]
Abstract
We investigated an outbreak of COVID-19 infection, which was traced back to a bathing pool at an entertainment venue, to explore the epidemiology of the outbreak, understand the transmissibility of the virus and analyse the influencing factors. Contact investigation and management were conducted to identify potential cases. Epidemiological investigation was carried out to determine the epidemiological and demographic characteristics of the outbreak. We estimated the secondary attack rate (SAR), incubation time and time-dependent reproductive number (Rt ) and explored the predisposing factors for cluster infection. The incubation time was 5.4 days and the serial interval (SI) was 4.4 days, with the rate of negative-valued SIs at 24.5%. The SAR at the bathing pool (3.3%) was relatively low due to its high temperature and humidity. The SAR was higher in the colleagues' cluster (20.5%) than in the family cluster (11.8%). Super-spreaders had a longer isolation delay time (p = .004). The Rt of the cluster decreased from the highest value of 3.88 on January 27, 2020 to 1.22 on February 6. Our findings suggest that the predisposing factors of the outbreak included close contact with an infected person, airtight and crowded spaces, temperature and humidity in the space and untimely isolation of patients and quarantine of contacts at the early stage of transmission. Measures to reduce the risk of infection at these gatherings and subsequent tracking of close contacts were effective.
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Affiliation(s)
- Changjun Bao
- Department of Acute Infectious Diseases Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.,NHC Key Laboratory of Enteric Pathogenic Microbiology, Nanjing, China.,Department of Epidemiology and Health Statistics, School of Public Health, Southeast University, Nanjing, China
| | - Enchun Pan
- Huaian Center for Disease Control and Prevention, Huaian, China
| | - Jing Ai
- Department of Acute Infectious Diseases Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China
| | - Qigang Dai
- Department of Acute Infectious Diseases Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China
| | - Ke Xu
- Department of Acute Infectious Diseases Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China
| | - Naiyang Shi
- Department of Epidemiology and Health Statistics, School of Public Health, Southeast University, Nanjing, China.,Key Laboratory of Environmental Medicine Engineering, Ministry of Education, Nanjing, China
| | - Qiang Gao
- Huaian Center for Disease Control and Prevention, Huaian, China
| | - Jianli Hu
- Department of Acute Infectious Diseases Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China
| | - Zhihang Peng
- School of Public Health, Nanjing Medical University, Nanjing, China
| | - Haodi Huang
- Department of Acute Infectious Diseases Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China
| | - Hui Jin
- Department of Epidemiology and Health Statistics, School of Public Health, Southeast University, Nanjing, China.,Key Laboratory of Environmental Medicine Engineering, Ministry of Education, Nanjing, China
| | - Fengcai Zhu
- Department of Acute Infectious Diseases Control and Prevention, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.,NHC Key Laboratory of Enteric Pathogenic Microbiology, Nanjing, China.,Department of Epidemiology and Health Statistics, School of Public Health, Southeast University, Nanjing, China
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Abstract
We explored the secondary attack rate in different types of contact with persons presymptomatic for coronavirus disease (COVID-19). Close contacts who lived with or had frequent contact with an index case-patient had a higher risk for COVID-19. Our findings provide population-based evidence for transmission from persons with presymptomatic COVID-19 infections.
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Kwok KO, Wong VWY, Wei WI, Wong SYS, Tang JWT. Epidemiological characteristics of the first 53 laboratory-confirmed cases of COVID-19 epidemic in Hong Kong, 13 February 2020. Euro Surveill 2020; 25:2000155. [PMID: 32347198 PMCID: PMC7189647 DOI: 10.2807/1560-7917.es.2020.25.16.2000155] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/14/2020] [Indexed: 01/06/2023] Open
Abstract
BackgroundCOVID-19, caused by SARS-CoV-2, first appeared in China and subsequently developed into an ongoing epidemic. Understanding epidemiological factors characterising the transmission dynamics of this disease is of fundamental importance.AimsThis study aimed to describe key epidemiological parameters of COVID-19 in Hong Kong.MethodsWe extracted data of confirmed COVID-19 cases and their close contacts from the publicly available information released by the Hong Kong Centre for Health Protection. We used doubly interval censored likelihood to estimate containment delay and serial interval, by fitting gamma, lognormal and Weibull distributions to respective empirical values using Bayesian framework with right truncation. A generalised linear regression model was employed to identify factors associated with containment delay. Secondary attack rate was also estimated.ResultsThe empirical containment delay was 6.39 days; whereas after adjusting for right truncation with the best-fit Weibull distribution, it was 10.4 days (95% CrI: 7.15 to 19.81). Containment delay increased significantly over time. Local source of infection and number of doctor consultations before isolation were associated with longer containment delay. The empirical serial interval was 4.58-6.06 days; whereas the best-fit lognormal distribution to 26 certain-and-probable infector-infectee paired data gave an estimate of 4.77 days (95% CrI: 3.47 to 6.90) with right-truncation. The secondary attack rate among close contacts was 11.7%.ConclusionWith a considerable containment delay and short serial interval, contact-tracing effectiveness may not be optimised to halt the transmission with rapid generations replacement. Our study highlights the transmission risk of social interaction and pivotal role of physical distancing in suppressing the epidemic.
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Affiliation(s)
- Kin On Kwok
- JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
- Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
- Shenzhen Research Institute of The Chinese University of Hong Kong, Shenzhen, China
| | - Valerie Wing Yu Wong
- JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Wan In Wei
- JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Samuel Yeung Shan Wong
- JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
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Banerjee E, Griffith J, Kenyon C, Christianson B, Strain A, Martin K, McMahon M, Bagstad E, Laine E, Hardy K, Grilli G, Walters J, Dunn D, Roddy M, Ehresmann K. Containing a measles outbreak in Minnesota, 2017: methods and challenges. Perspect Public Health 2019; 140:162-171. [PMID: 31480896 DOI: 10.1177/1757913919871072] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AIMS We report on a measles outbreak largely occurring in Minnesota's under-vaccinated Somali community in the spring of 2017. The outbreak was already into its third generation when the first two cases were confirmed, and rapid public health actions were needed. The aim of our response was to quickly end transmission and contain the outbreak. METHODS The state public health department performed laboratory testing on suspect cases and activated an Incident Command staffed by subject matter experts that was operational within 2 h of case confirmation. Epidemiologic interviews identified exposures in settings where risk of transmission was high, that is, healthcare, childcare, and school settings. Vaccination status of exposed persons was assessed, and postexposure prophylaxis (PEP) was offered, if applicable. Exposed persons who did not receive PEP were excluded from childcare centers or schools for 21 days. An accelerated statewide measles, mumps, and rubella (MMR) recommendation was made for Somali Minnesota children and children in affected outbreak counties. Partnerships with the Somali Minnesota community were deepened, building off outreach work done with the community since 2008. RESULTS Public health identified 75 measles cases from 30 March to 25 August 2017: 43% were female, 81% Somali Minnesotan, 91% unvaccinated, and 28% hospitalized. The median age of cases was 2 years (range: 3 months-57 years). Most transmission (78%) occurred in childcare centers and households. A secondary attack rate of 91% was calculated for unvaccinated household contacts. Over 51,000 doses of MMR were administered during the outbreak above expected baseline. At least 8490 individuals were exposed to measles; 155 individuals received PEP; and over 500 persons were excluded from childcare and school. State and key public health partners spent an estimated $2.3 million on response. CONCLUSION This outbreak demonstrates the necessity of immediate, targeted disease control actions and strong public health, healthcare, and community partnerships to end a measles outbreak.
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Affiliation(s)
- E Banerjee
- Infectious Disease Epidemiology, Prevention and Control, Minnesota Department of Health, 625 Robert St. N., St. Paul, MN 55164, USA
| | - J Griffith
- Minnesota Department of Health, St. Paul, MN, USA
| | - C Kenyon
- Minnesota Department of Health, St. Paul, MN, USA
| | | | - A Strain
- Minnesota Department of Health, St. Paul, MN, USA
| | - K Martin
- Minnesota Department of Health, St. Paul, MN, USA
| | - M McMahon
- Minnesota Department of Health, St. Paul, MN, USA
| | - E Bagstad
- Hennepin County Human Services and Public Health, Hopkins, MN, USA
| | - E Laine
- Minnesota Department of Health, St. Paul, MN, USA
| | - K Hardy
- Minnesota Department of Health, St. Paul, MN, USA
| | - G Grilli
- Minnesota Department of Health, St. Paul, MN, USA
| | - J Walters
- Minnesota Department of Health, St. Paul, MN, USA
| | - D Dunn
- Minnesota Department of Health, St. Paul, MN, USA
| | - M Roddy
- Minnesota Department of Health, St. Paul, MN, USA
| | - K Ehresmann
- Minnesota Department of Health, St. Paul, MN, USA
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Glynn JR, Bower H, Johnson S, Turay C, Sesay D, Mansaray SH, Kamara O, Kamara AJ, Bangura MS, Checchi F. Variability in Intrahousehold Transmission of Ebola Virus, and Estimation of the Household Secondary Attack Rate. J Infect Dis 2019; 217:232-237. [PMID: 29140442 PMCID: PMC5853870 DOI: 10.1093/infdis/jix579] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 11/06/2017] [Indexed: 11/14/2022] Open
Abstract
Transmission between family members accounts for most Ebola virus transmission, but little is known about determinants of intrahousehold spread. From detailed exposure histories, intrahousehold transmission chains were created for 94 households of Ebola survivors in Sierra Leone: 109 (co-)primary cases gave rise to 317 subsequent cases (0-100% of those exposed). Larger households were more likely to have subsequent cases, and the proportion of household members affected depended on individual and household-level factors. More transmissions occurred from older than from younger cases, and from those with more severe disease. The estimated household secondary attack rate was 18%.
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Affiliation(s)
- Judith R Glynn
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom
- Correspondence: J. R. Glynn, PhD, FRCP, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK ()
| | - Hilary Bower
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom
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40
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Fang LQ, Yang Y, Jiang JF, Yao HW, Kargbo D, Li XL, Jiang BG, Kargbo B, Tong YG, Wang YW, Liu K, Kamara A, Dafae F, Kanu A, Jiang RR, Sun Y, Sun RX, Chen WJ, Ma MJ, Dean NE, Thomas H, Longini IM, Halloran ME, Cao WC. Transmission dynamics of Ebola virus disease and intervention effectiveness in Sierra Leone. Proc Natl Acad Sci U S A 2016; 113:4488-93. [PMID: 27035948 PMCID: PMC4843458 DOI: 10.1073/pnas.1518587113] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sierra Leone is the most severely affected country by an unprecedented outbreak of Ebola virus disease (EVD) in West Africa. Although successfully contained, the transmission dynamics of EVD and the impact of interventions in the country remain unclear. We established a database of confirmed and suspected EVD cases from May 2014 to September 2015 in Sierra Leone and mapped the spatiotemporal distribution of cases at the chiefdom level. A Poisson transmission model revealed that the transmissibility at the chiefdom level, estimated as the average number of secondary infections caused by a patient per week, was reduced by 43% [95% confidence interval (CI): 30%, 52%] after October 2014, when the strategic plan of the United Nations Mission for Emergency Ebola Response was initiated, and by 65% (95% CI: 57%, 71%) after the end of December 2014, when 100% case isolation and safe burials were essentially achieved, both compared with before October 2014. Population density, proximity to Ebola treatment centers, cropland coverage, and atmospheric temperature were associated with EVD transmission. The household secondary attack rate (SAR) was estimated to be 0.059 (95% CI: 0.050, 0.070) for the overall outbreak. The household SAR was reduced by 82%, from 0.093 to 0.017, after the nationwide campaign to achieve 100% case isolation and safe burials had been conducted. This study provides a complete overview of the transmission dynamics of the 2014-2015 EVD outbreak in Sierra Leone at both chiefdom and household levels. The interventions implemented in Sierra Leone seem effective in containing the epidemic, particularly in interrupting household transmission.
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Affiliation(s)
- Li-Qun Fang
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Yang Yang
- Department of Biostatistics, University of Florida, Gainesville, FL 32610; Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610
| | - Jia-Fu Jiang
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Hong-Wu Yao
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - David Kargbo
- The Sierra Leone Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Xin-Lou Li
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Bao-Gui Jiang
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Brima Kargbo
- The Sierra Leone Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Yi-Gang Tong
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Ya-Wei Wang
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Kun Liu
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Abdul Kamara
- The Sierra Leone Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Foday Dafae
- The Sierra Leone Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Alex Kanu
- Sierra Leone-China Friendship Hospital, Freetown, Sierra Leone
| | - Rui-Ruo Jiang
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Ye Sun
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Ruo-Xi Sun
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China; Anhui Medical University, Hefei 230032, People's Republic of China
| | - Wan-Jun Chen
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Mai-Juan Ma
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China
| | - Natalie E Dean
- Department of Biostatistics, University of Florida, Gainesville, FL 32610; Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610
| | - Harold Thomas
- The Sierra Leone Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Ira M Longini
- Department of Biostatistics, University of Florida, Gainesville, FL 32610; Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610
| | - M Elizabeth Halloran
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Wu-Chun Cao
- The State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China;
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Dean NE, Halloran ME, Yang Y, Longini IM. Transmissibility and Pathogenicity of Ebola Virus: A Systematic Review and Meta-analysis of Household Secondary Attack Rate and Asymptomatic Infection. Clin Infect Dis 2016; 62:1277-1286. [PMID: 26932131 DOI: 10.1093/cid/ciw114] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 02/19/2016] [Indexed: 11/14/2022] Open
Abstract
Factors affecting our ability to control an Ebola outbreak include transmissibility of the virus and the proportion of transmissions occurring asymptomatically. We performed a meta-analysis of Ebola household secondary attack rate (SAR), disaggregating by type of exposure (direct contact, no direct contact, nursing care, direct contact but no nursing care). The estimated overall household SAR is 12.5% (95% confidence interval [CI], 8.6%-16.3%). Transmission was driven by direct contact, with little transmission occurring in its absence (SAR, 0.8% [95% CI, 0%-2.3%]). The greatest risk factor was the provision of nursing care (SAR, 47.9% [95% CI, 23.3%-72.6%]). There was evidence of a decline in household SAR for direct contact between 1976 and 2014 (P = .018). We estimate that 27.1% (95% CI, 14.5%-39.6%) of Ebola infections are asymptomatic. Our findings suggest that surveillance and containment measures should be effective for controlling Ebola.
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Affiliation(s)
- Natalie E Dean
- Department of Biostatistics, University of Florida, Gainesville
| | - M Elizabeth Halloran
- Department of Biostatistics, University of Washington.,Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Yang Yang
- Department of Biostatistics, University of Florida, Gainesville
| | - Ira M Longini
- Department of Biostatistics, University of Florida, Gainesville
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Yom-Tov E, Johansson-Cox I, Lampos V, Hayward AC. Estimating the secondary attack rate and serial interval of influenza-like illnesses using social media. Influenza Other Respir Viruses 2016; 9:191-9. [PMID: 25962320 PMCID: PMC4474495 DOI: 10.1111/irv.12321] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2015] [Indexed: 12/05/2022] Open
Abstract
Objectives Knowledge of the secondary attack rate (SAR) and serial interval (SI) of influenza is important for assessing the severity of seasonal epidemics of the virus. To date, such estimates have required extensive surveys of target populations. Here, we propose a method for estimating the intrafamily SAR and SI from postings on the Twitter social network. This estimate is derived from a large number of people reporting ILI symptoms in them and\or their immediate family members. Design We analyze data from the 2012–2013 and the 2013–2014 influenza seasons in England and find that increases in the estimated SAR precede increases in ILI rates reported by physicians. Results We hypothesize that observed variations in the peak value of SAR are related to the appearance of specific strains of the virus and demonstrate this by comparing the changes in SAR values over time in relation to known virology. In addition, we estimate SI (the average time between cases) as 2·41 days for 2012 and 2·48 days for 2013. Conclusions The proposed method can assist health authorities by providing near-real-time estimation of SAR and SI, and especially in alerting to sudden increases thereof.
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Affiliation(s)
| | - Ingemar Johansson-Cox
- Department of Computer Science, University College London, London, UK.,Department of Computer Science, University of Copenhagen, Copenhagen, Denmark
| | - Vasileios Lampos
- Department of Computer Science, University College London, London, UK
| | - Andrew C Hayward
- Farr Institute of Health Informatics Research, University College London, London, UK
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43
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Buhnerkempe MG, Gostic K, Park M, Ahsan P, Belser JA, Lloyd-Smith JO. Mapping influenza transmission in the ferret model to transmission in humans. eLife 2015; 4. [PMID: 26329460 PMCID: PMC4586390 DOI: 10.7554/elife.07969] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 09/02/2015] [Indexed: 12/27/2022] Open
Abstract
The controversy surrounding 'gain-of-function' experiments on high-consequence avian influenza viruses has highlighted the role of ferret transmission experiments in studying the transmission potential of novel influenza strains. However, the mapping between influenza transmission in ferrets and in humans is unsubstantiated. We address this gap by compiling and analyzing 240 estimates of influenza transmission in ferrets and humans. We demonstrate that estimates of ferret secondary attack rate (SAR) explain 66% of the variation in human SAR estimates at the subtype level. Further analysis shows that ferret transmission experiments have potential to identify influenza viruses of concern for epidemic spread in humans, though small sample sizes and biological uncertainties prevent definitive classification of human transmissibility. Thus, ferret transmission experiments provide valid predictions of pandemic potential of novel influenza strains, though results should continue to be corroborated by targeted virological and epidemiological research. DOI:http://dx.doi.org/10.7554/eLife.07969.001 Every year, thousands of people develop influenza (flu). After being infected by the influenza virus, the immune systems of most people adapt to fight off the virus if it is encountered again. However, there are many different strains of influenza, and new strains constantly evolve. Therefore, although someone may have developed resistance to one previously encountered strain, they can still become ill if another strain infects them. Different strains of the influenza virus have different abilities to spread between people and make them ill. One way that scientists assess whether a particular strain of influenza is a threat to people is by studying ferrets, which develop many of the same flu symptoms as humans. However, questions have been raised over how accurately ferret studies reflect whether a particular virus strain will spread between humans. Controversy has also arisen over experiments in which ferrets are infected with genetically engineered strains of influenza that mimic how a strain that has evolved in birds could adapt to cause a pandemic in humans. In 2014, the United States government suggested that such research should be temporarily stopped until more is known about the risks and usefulness of these studies. Now, Buhnerkempe, Gostic et al. have compared the results of 240 ferret and human studies that aimed to assess how easily strains of influenza spread. Specifically, the studies looked at how often a healthy ferret or human became ill when exposed to an animal or human infected with a particular strain of influenza. The results of the ferret transmission studies matched well with transmission patterns observed in human studies. Ferret studies that assessed how the influenza virus is transmitted through the air via sneezes and coughs were particularly good at predicting how the virus spreads in humans. But Buhnerkempe, Gostic et al. caution that ferret studies are not always accurate, partly because they involve small numbers of animals, which can skew the results. There also needs to be more effort to standardize the procedures and measurements used in ferret studies. Still, the analysis suggests that overall, ferret studies are a useful tool for making an initial prediction of which influenza strains may cause a pandemic in humans, which can then be verified using other methods. DOI:http://dx.doi.org/10.7554/eLife.07969.002
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Affiliation(s)
- Michael G Buhnerkempe
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, United States
| | - Katelyn Gostic
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, United States
| | - Miran Park
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, United States
| | - Prianna Ahsan
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, United States
| | - Jessica A Belser
- Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, United States
| | - James O Lloyd-Smith
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, United States
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44
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Chowell G, Nishiura H. Toward unbiased assessment of treatment and prevention: modeling household transmission of pandemic influenza. BMC Med 2012; 10:118. [PMID: 23046539 DOI: 10.1186/1741-7015-10-118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 10/09/2012] [Indexed: 11/23/2022] Open
Abstract
Providing valid and reliable estimates of the transmissibility and severity of pandemic influenza in real time is key to guide public health policymaking. In particular, early estimates of the transmissibility are indispensable for determining the type and intensity of interventions. A recent study by House and colleagues in BMC Medicine devised a stochastic transmission model to estimate the unbiased risk of transmission within households, applying the method to datasets of the 2009 A/H1N1 influenza pandemic. Here, we discuss future challenges in household transmission studies and underscore the need to systematically collect epidemiological data to decipher the household transmission dynamics. We emphasize the need to consider three critical issues for future improvements: (i) capturing age-dependent heterogeneity within households calls for intensive modeling efforts, (ii) the timeline of observation during the course of an epidemic and the length of follow-up should be aligned with study objectives, and (iii) the use of laboratory methods, especially molecular techniques, is encouraged to distinguish household transmissions from those arising in the community.See related article: http://www.biomedcentral.com/1741-7015/10/117.
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