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Dahlgren FS, Foppa IM, Stockwell MS, Vargas CY, LaRussa P, Reed C. Household transmission of influenza A and B within a prospective cohort during the 2013-2014 and 2014-2015 seasons. Stat Med 2021; 40:6260-6276. [PMID: 34580901 PMCID: PMC9293304 DOI: 10.1002/sim.9181] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/22/2021] [Accepted: 08/15/2021] [Indexed: 01/01/2023]
Abstract
People living within the same household as someone ill with influenza are at increased risk of infection. Here, we use Markov chain Monte Carlo methods to partition the hazard of influenza illness within a cohort into the hazard from the community and the hazard from the household. During the 2013‐2014 influenza season, 49 (4.7%) of the 1044 people enrolled in a community surveillance cohort had an acute respiratory illness (ARI) attributable to influenza. During the 2014‐2015 influenza season, 50 (4.7%) of the 1063 people in the cohort had an ARI attributable to influenza. The secondary attack rate from a household member was 2.3% for influenza A (H1) during 2013‐2014, 5.3% for influenza B during 2013‐2014, and 7.6% for influenza A (H3) during 2014‐2015. Living in a household with a person ill with influenza increased the risk of an ARI attributable to influenza up to 350%, depending on the season and the influenza virus circulating within the household.
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Affiliation(s)
- F Scott Dahlgren
- Influenza Division, Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Ivo M Foppa
- Influenza Division, Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.,Battelle Memorial Institute, Atlanta, Georgia, USA
| | - Melissa S Stockwell
- Division of Child and Adolescent Health, Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA.,Department of Population and Family Health, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Celibell Y Vargas
- Division of Child and Adolescent Health, Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Philip LaRussa
- Division of Pediatric Infectious Diseases, Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Carrie Reed
- Influenza Division, Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Cohen C, Kleynhans J, Moyes J, McMorrow ML, Treurnicht FK, Hellferscee O, Mathunjwa A, von Gottberg A, Wolter N, Martinson NA, Kahn K, Lebina L, Mothlaoleng K, Wafawanaka F, Gómez-Olivé FX, Mkhencele T, Mathee A, Piketh S, Language B, Tempia S. Asymptomatic transmission and high community burden of seasonal influenza in an urban and a rural community in South Africa, 2017-18 (PHIRST): a population cohort study. Lancet Glob Health 2021; 9:e863-e874. [PMID: 34019838 PMCID: PMC8262603 DOI: 10.1016/s2214-109x(21)00141-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/23/2021] [Accepted: 02/26/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND Data on influenza community burden and transmission are important to plan interventions especially in resource-limited settings. However, data are limited, particularly from low-income and middle-income countries. We aimed to evaluate the community burden and transmission of influenza in a rural and an urban setting in South Africa. METHODS In this prospective cohort study approximately 50 households were selected sequentially from both a rural setting (Agincourt, Mpumalanga Province, South Africa; with a health and sociodemographic surveillance system) and an urban setting (Klerksdorp, Northwest Province, South Africa; using global positioning system data), enrolled, and followed up for 10 months in 2017 and 2018. Different households were enrolled in each year. Households of more than two individuals in which 80% or more of the occupants agreed to participate were included in the study. Nasopharyngeal swabs were collected twice per week from participating household members irrespective of symptoms and tested for influenza using real-time RT-PCR. The primary outcome was the incidence of influenza infection, defined as the number of real-time RT-PCR-positive episodes divided by the person-time under observation. Household cumulative infection risk (HCIR) was defined as the number of subsequent infections within a household following influenza introduction. FINDINGS 81 430 nasopharyngeal samples were collected from 1116 participants in 225 households (follow-up rate 88%). 917 (1%) tested positive for influenza; 178 (79%) of 225 households had one or more influenza-positive individual. The incidence of influenza infection was 43·6 (95% CI 39·8-47·7) per 100 person-seasons. 69 (17%) of 408 individuals who had one influenza infection had a repeat influenza infection during the same season. The incidence (67·4 per 100 person-seasons) and proportion with repeat infections (22 [23%] of 97 children) were highest in children younger than 5 years and decreased with increasing age (p<0·0001). Overall, 268 (56%) of 478 infections were symptomatic and 66 (14%) of 478 infections were medically attended. The overall HCIR was 10% (109 of 1088 exposed household members infected [95% CI 9-13%). Transmission (HCIR) from index cases was highest in participants aged 1-4 years (16%; 40 of 252 exposed household members) and individuals with two or more symptoms (17%; 68 of 396 exposed household members). Individuals with asymptomatic influenza transmitted infection to 29 (6%) of 509 household contacts. HIV infection, affecting 167 (16%) of 1075 individuals, was not associated with increased incidence or HCIR. INTERPRETATION Approximately half of influenza infections were symptomatic, with asymptomatic individuals transmitting influenza to 6% of household contacts. This suggests that strategies, such as quarantine and isolation, might be ineffective to control influenza. Vaccination of children, with the aim of reducing influenza transmission might be effective in African settings given the young population and high influenza burden. FUNDING US Centers for Disease Control and Prevention.
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Affiliation(s)
- Cheryl Cohen
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
| | - Jackie Kleynhans
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Jocelyn Moyes
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Meredith L McMorrow
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA; Influenza Program, Centers for Disease Control and Prevention, Pretoria, South Africa
| | - Florette K Treurnicht
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Orienka Hellferscee
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
| | - Azwifarwi Mathunjwa
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Anne von Gottberg
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
| | - Nicole Wolter
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
| | - Neil A Martinson
- Perinatal HIV Research Unit, South African Medical Research Council, Soweto Matlosana Collaborating Centre for HIV/AIDS and Tuberculosis, University of the Witwatersrand, Johannesburg, South Africa; Department of Science and Technology, National Research Foundations, Centre of Excellence for Biomedical Tuberculosis Research, University of the Witwatersrand, Johannesburg, South Africa; Center for Tuberculosis Research, Johns Hopkins University, Baltimore, MD, USA
| | - Kathleen Kahn
- South African Medical Research Council Rural Public Health and Health Transitions Research Unit (Agincourt), University of the Witwatersrand, Johannesburg, South Africa
| | - Limakatso Lebina
- Perinatal HIV Research Unit, South African Medical Research Council, Soweto Matlosana Collaborating Centre for HIV/AIDS and Tuberculosis, University of the Witwatersrand, Johannesburg, South Africa
| | - Katlego Mothlaoleng
- Perinatal HIV Research Unit, South African Medical Research Council, Soweto Matlosana Collaborating Centre for HIV/AIDS and Tuberculosis, University of the Witwatersrand, Johannesburg, South Africa
| | - Floidy Wafawanaka
- South African Medical Research Council Rural Public Health and Health Transitions Research Unit (Agincourt), University of the Witwatersrand, Johannesburg, South Africa
| | - Francesc Xavier Gómez-Olivé
- South African Medical Research Council Rural Public Health and Health Transitions Research Unit (Agincourt), University of the Witwatersrand, Johannesburg, South Africa
| | - Thulisa Mkhencele
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Angela Mathee
- Environment and Health Research Unit, South African Medical Research Council, Johannesburg, South Africa
| | - Stuart Piketh
- Unit for Environmental Science and Management, Climatology Research Group, North-West University, Potchefstroom, South Africa
| | - Brigitte Language
- Unit for Environmental Science and Management, Climatology Research Group, North-West University, Potchefstroom, South Africa
| | - Stefano Tempia
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa; Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA; Influenza Program, Centers for Disease Control and Prevention, Pretoria, South Africa; MassGenics, Duluth, GA, USA
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Lagare A, Rajatonirina S, Testa J, Mamadou S. The epidemiology of seasonal influenza after the 2009 influenza pandemic in Africa: a systematic review. Afr Health Sci 2020; 20:1514-1536. [PMID: 34394213 PMCID: PMC8351825 DOI: 10.4314/ahs.v20i4.5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Background Influenza infection is a serious public health problem that causes an estimated 3 to 5 million cases and 250,000 deaths worldwide every year. The epidemiology of influenza is well-documented in high- and middle-income countries, however minimal effort had been made to understand the epidemiology, burden and seasonality of influenza in Africa. This study aims to assess the state of knowledge of seasonal influenza epidemiology in Africa and identify potential data gaps for policy formulation following the 2009 pandemic. Method We reviewed articles from Africa published into four databases namely: MEDLINE (PubMed), Google Scholar, Cochrane Library and Scientific Research Publishing from 2010 to 2019. Results We screened titles and abstracts of 2070 studies of which 311 were selected for full content evaluation and 199 studies were considered. Selected articles varied substantially on the basis of the topics they addressed covering the field of influenza surveillance (n=80); influenza risk factors and co-morbidities (n=15); influenza burden (n=37); influenza vaccination (n=40); influenza and other respiratory pathogens (n=22) and influenza diagnosis (n=5). Conclusion Significant progress has been made since the last pandemic in understanding the influenza epidemiology in Africa. However, efforts still remain for most countries to have sufficient data to allow countries to prioritize strategies for influenza prevention and control.
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Affiliation(s)
- Adamou Lagare
- Centre de Recherche Médicale et Sanitaire (CERMES), Niamey, Niger
| | | | - Jean Testa
- Centre de Recherche Médicale et Sanitaire (CERMES), Niamey, Niger
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