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Chen PZ, Bobrovitz N, Premji Z, Koopmans M, Fisman DN, Gu FX. Heterogeneity in transmissibility and shedding SARS-CoV-2 via droplets and aerosols. eLife 2021; 10:e65774. [PMID: 33861198 PMCID: PMC8139838 DOI: 10.7554/elife.65774] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/15/2021] [Indexed: 01/08/2023] Open
Abstract
Background Which virological factors mediate overdispersion in the transmissibility of emerging viruses remains a long-standing question in infectious disease epidemiology. Methods Here, we use systematic review to develop a comprehensive dataset of respiratory viral loads (rVLs) of SARS-CoV-2, SARS-CoV-1 and influenza A(H1N1)pdm09. We then comparatively meta-analyze the data and model individual infectiousness by shedding viable virus via respiratory droplets and aerosols. Results The analyses indicate heterogeneity in rVL as an intrinsic virological factor facilitating greater overdispersion for SARS-CoV-2 in the COVID-19 pandemic than A(H1N1)pdm09 in the 2009 influenza pandemic. For COVID-19, case heterogeneity remains broad throughout the infectious period, including for pediatric and asymptomatic infections. Hence, many COVID-19 cases inherently present minimal transmission risk, whereas highly infectious individuals shed tens to thousands of SARS-CoV-2 virions/min via droplets and aerosols while breathing, talking and singing. Coughing increases the contagiousness, especially in close contact, of symptomatic cases relative to asymptomatic ones. Infectiousness tends to be elevated between 1 and 5 days post-symptom onset. Conclusions Intrinsic case variation in rVL facilitates overdispersion in the transmissibility of emerging respiratory viruses. Our findings present considerations for disease control in the COVID-19 pandemic as well as future outbreaks of novel viruses. Funding Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant program, NSERC Senior Industrial Research Chair program and the Toronto COVID-19 Action Fund.
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Affiliation(s)
- Paul Z Chen
- Department of Chemical Engineering & Applied Chemistry, University of TorontoTorontoCanada
| | - Niklas Bobrovitz
- Temerty Faculty of Medicine, University of TorontoTorontoCanada
- Department of Critical Care Medicine, Cumming School of Medicine, University of CalgaryCalgaryCanada
- O'Brien Institute of Public Health, University of CalgaryCalgaryCanada
| | - Zahra Premji
- Libraries & Cultural Resources, University of CalgaryCalgaryCanada
| | - Marion Koopmans
- Department of Viroscience, Erasmus University Medical CenterRotterdamNetherlands
| | - David N Fisman
- Division of Epidemiology, Dalla Lana School of Public Health, University of TorontoTorontoCanada
- Division of Infectious Diseases, Temerty Faculty of Medicine, University of TorontoTorontoCanada
| | - Frank X Gu
- Department of Chemical Engineering & Applied Chemistry, University of TorontoTorontoCanada
- Institute of Biomedical Engineering, University of TorontoTorontoCanada
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Huang PY, Su CP, Liu SW, Kao KC, Hsieh YC, Huang CT. Correlation between Negative Rapid Influenza Diagnostic Test and Severe Disease in Hospitalized Adults with Laboratory-Confirmed Influenza Virus Infection. Am J Trop Med Hyg 2020; 103:1642-1648. [PMID: 32876004 PMCID: PMC7543834 DOI: 10.4269/ajtmh.19-0444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
False-negative rapid influenza diagnostic test (RIDT) results could mislead physicians to exclude an influenza diagnosis. We sought to evaluate the association between negative RIDT and intensive care unit (ICU) admission. We reviewed data from hospitalized adults with laboratory-confirmed influenza virus infections in a tertiary referral hospital in Taiwan from July 2009 to February 2011. The diagnosis was documented by real-time PCR or virus culture. Of 134 hospitalized adults infected with influenza virus, 38 (28%) were admitted to the ICU. Compared with RIDT-positive patients, the percentage of ICU admission was significantly higher among RIDT-negative patients (46% versus 13%, P < 0.001). The RIDT-negative patients had higher percentages of lower respiratory symptoms and more chest radiograph infiltrates. The time interval between the RIDT and antiviral treatment was longer in RIDT-negative than RIDT-positive patients (1.94 days versus 0.03 days, P < 0.001). Among patients presenting with mild illness, only a negative RIDT and delayed antiviral treatment were associated with ICU admission after adjusting for potential confounding factors. To conclude, patients with a negative RIDT were more likely to have severe disease and a delay in initiating antiviral treatment. Our findings should help improve treatment outcomes of hospitalized patients with influenza infection.
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Affiliation(s)
- Po-Yen Huang
- Division of Infectious Diseases, Department of Internal Medicine, Chang-Gung Memorial Hospital, Chang-Gung University College of Medicine, Taoyuan, Taiwan
| | - Chia-Ping Su
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.,Taiwan Centers for Disease Control, Ministry of Health and Welfare, Taipei, Taiwan
| | - Shi-Wei Liu
- Division of Infectious Diseases, Department of Internal Medicine, Chang-Gung Memorial Hospital, Chang-Gung University College of Medicine, Taoyuan, Taiwan
| | - Kuo-Chin Kao
- Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan.,Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Yu-Chia Hsieh
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Ching-Tai Huang
- Division of Infectious Diseases, Department of Internal Medicine, Chang-Gung Memorial Hospital, Chang-Gung University College of Medicine, Taoyuan, Taiwan
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Lalueza A, Folgueira D, Muñoz-Gallego I, Trujillo H, Laureiro J, Hernández-Jiménez P, Moral-Jiménez N, Castillo C, Ayuso B, Díaz-Pedroche C, Torres M, Arrieta E, Arévalo-Cañas C, Madrid O, Lumbreras C. Influence of viral load in the outcome of hospitalized patients with influenza virus infection. Eur J Clin Microbiol Infect Dis 2019; 38:667-673. [PMID: 30820840 PMCID: PMC7102091 DOI: 10.1007/s10096-019-03514-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 02/14/2019] [Indexed: 01/30/2023]
Abstract
The role of viral load in the outcome of patients requiring hospital admission due to influenza is not well established. We aim to assess if there is an association between the viral load and the outcome in hospitalized patients with a confirmed influenza virus infection. A retrospective observational study including all adult patients who were hospitalized in our center with a confirmed influenza virus infection from January to May 2016. Viral load was measured by real-time reverse-transcriptase–polymerase chain reaction (rRT-PCR) cycle threshold (Ct) value on upper respiratory tract samples. Its value was categorized into three groups (low Ct, ≤ 20; intermediate Ct, > 20–30; and high Ct, > 30). Two hundred thirty-nine patients were included. Influenza A/H1N1pdm09 was isolated in 207 cases (86.6%). The mean Ct value was 26.69 ± 5.81. The viral load was higher in the unvaccinated group when compared with the vaccinated patients (Ct 25.17 ± 5.55 vs. 27.58 ± 4.97, p = 0.004). Only 27 patients (11.29%) presented a high viral load. Patients with a high viral load more often showed abnormal findings on chest X-ray (p = 0.015) and lymphopenia (p = 0.097). By contrast, there were no differences between the three groups (according to viral load), in associated pneumonia, respiratory failure, need for mechanical ventilation, sepsis, or in-hospital mortality. Our findings suggest that in patients admitted to the hospital with confirmed influenza virus infection (mostly A/H1N1pdm09), a high viral load is associated with a higher presence of abnormal findings on chest X-ray but not with a significant worse prognosis. In these cases, standardized quantitative PCR could be useful.
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Affiliation(s)
- Antonio Lalueza
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain. .,Department of Medicine, School of Medicine, Complutense University, Madrid, Spain. .,Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.
| | - Dolores Folgueira
- Department of Medicine, School of Medicine, Complutense University, Madrid, Spain.,Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.,Department of Microbiology, University Hospital 12 de Octubre, Madrid, Spain
| | - Irene Muñoz-Gallego
- Department of Microbiology, University Hospital 12 de Octubre, Madrid, Spain
| | - Hernando Trujillo
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Jaime Laureiro
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Pilar Hernández-Jiménez
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | | | - Cristina Castillo
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Blanca Ayuso
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Carmen Díaz-Pedroche
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain.,Department of Medicine, School of Medicine, Complutense University, Madrid, Spain
| | - Marta Torres
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Estibaliz Arrieta
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Coral Arévalo-Cañas
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Olaya Madrid
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Carlos Lumbreras
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain.,Department of Medicine, School of Medicine, Complutense University, Madrid, Spain.,Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.,Infectious Diseases Unit, University Hospital 12 de Octubre, Madrid, Spain
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De Conto F, Conversano F, Medici MC, Ferraglia F, Pinardi F, Arcangeletti MC, Chezzi C, Calderaro A. Epidemiology of human respiratory viruses in children with acute respiratory tract infection in a 3-year hospital-based survey in Northern Italy. Diagn Microbiol Infect Dis 2019; 94:260-267. [PMID: 30745224 PMCID: PMC7126416 DOI: 10.1016/j.diagmicrobio.2019.01.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 01/08/2019] [Accepted: 01/09/2019] [Indexed: 12/13/2022]
Abstract
Acute respiratory tract infections (ARTIs) are among the leading causes of morbidity and mortality in children. The viral etiology of ARTIs was investigated over 3 years (October 2012–September 2015) in 2575 children in Parma, Italy, using indirect immunofluorescent staining of respiratory samples for viral antigens, cell culture, and molecular assays. Respiratory viruses were detected in 1299 cases (50.44%); 1037 (79.83%) were single infections and 262 (20.17%) mixed infections. The highest infection incidence was in children aged >6 months to ≤3 years (57.36%). Human respiratory syncytial virus (27.12%) and human adenovirus (23.58%) were the most common viruses identified. The virus detection rate decreased significantly between the first and third epidemic season (53.9% vs. 43.05%, P < 0.0001). The simultaneous use of different diagnostic tools allowed us to identify a putative viral etiology in half the children examined and to provide an estimate of the epidemiology and seasonality of respiratory viruses associated with ARTIs. Respiratory viruses were assessed in children from October 2012 to September 2015. Viruses were detected using antigen and molecular assays, and cell culture. Respiratory syncytial virus and adenovirus were the most common viruses detected. Influenza virus and respiratory syncytial virus detection showed seasonal variation. Respiratory virus detection was highest in children aged >6 months to ≤3 years.
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Affiliation(s)
- Flora De Conto
- Department of Medicine and Surgery, University of Parma, Viale A. Gramsci 14, 43126 Parma, Italy.
| | - Francesca Conversano
- Department of Medicine and Surgery, University of Parma, Viale A. Gramsci 14, 43126 Parma, Italy
| | - Maria Cristina Medici
- Department of Medicine and Surgery, University of Parma, Viale A. Gramsci 14, 43126 Parma, Italy
| | - Francesca Ferraglia
- Department of Medicine and Surgery, University of Parma, Viale A. Gramsci 14, 43126 Parma, Italy
| | - Federica Pinardi
- Department of Medicine and Surgery, University of Parma, Viale A. Gramsci 14, 43126 Parma, Italy
| | | | - Carlo Chezzi
- Department of Medicine and Surgery, University of Parma, Viale A. Gramsci 14, 43126 Parma, Italy
| | - Adriana Calderaro
- Department of Medicine and Surgery, University of Parma, Viale A. Gramsci 14, 43126 Parma, Italy
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5
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Tunheim G, Laake I, Robertson AH, Waalen K, Hungnes O, Naess LM, Cox RJ, Mjaaland S, Trogstad L. Antibody levels in a cohort of pregnant women after the 2009 influenza A(H1N1) pandemic: Waning and association with self-reported severity and duration of illness. Influenza Other Respir Viruses 2018; 13:191-200. [PMID: 30536590 PMCID: PMC6379636 DOI: 10.1111/irv.12623] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 11/05/2018] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND A population-based pregnancy cohort was established in Norway to study potential effects of exposure to the 2009 influenza pandemic or pandemic vaccination during pregnancy. OBJECTIVES We studied maternal A(H1N1)pdm09-specific hemagglutination inhibition (HI)-titer levels and waning in women with influenza-like illness (ILI) in pregnancy compared to vaccinated women. Moreover, we studied the association between HI-titers and self-reported severity and duration of ILI. METHODS HI-titers against the pandemic virus were measured in maternal blood samples obtained at birth, 3-9 months after exposure, and linked with information about pregnancy, influenza and vaccination from national registries and a cohort questionnaire. RESULTS Among 1821 pregnant women included, 43.7% were unvaccinated and 19.3% of these had ILI. HI-titers were low (geometric mean titer (GMT) 11.3) in the unvaccinated women with ILI. Higher HI-titers (GMT 37.8) were measured in the vaccinated women. Estimated HI-titer waning was similar for vaccinated women and women with ILI. Most ILI episodes were moderate and lasted 3-5 days. Women with ILI reporting specific influenza symptoms such as fever or cough had higher HI-titers than women without these symptoms. Women who reported being "very ill" or illness duration of >5 days had higher HI-titers than women reporting less severe illness or illness of shorter duration, respectively. CONCLUSIONS Antibody waning was similar in vaccinated women and women with ILI. More severe ILI or longer duration of illness was associated with higher HI-titers. Most unvaccinated pregnant women with ILI had low HI-titers, probably due to moderate illness and HI-titer waning between exposure and sampling.
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Affiliation(s)
- Gro Tunheim
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.,K. G. Jebsen Centre for Influenza Vaccine Research, University of Oslo, Oslo, Norway
| | - Ida Laake
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Anna Hayman Robertson
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Kristian Waalen
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Olav Hungnes
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Lisbeth M Naess
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Rebecca J Cox
- K. G. Jebsen Centre for Influenza Vaccine Research, University of Oslo, Oslo, Norway.,The Influenza Centre, Department of Clinical Science, University of Bergen, Bergen, Norway.,Department of Research and Development, Haukeland University Hospital, Bergen, Norway
| | - Siri Mjaaland
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.,K. G. Jebsen Centre for Influenza Vaccine Research, University of Oslo, Oslo, Norway
| | - Lill Trogstad
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
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6
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Yang JH, Huang PY, Shie SS, Yang S, Tsao KC, Wu TL, Wu TS, Huang CT. Diagnostic performance of the Sofia® influenza A+B fluorescent immunoassay in adult outpatients in Northern Taiwan. J Med Virol 2018; 90:1010-1018. [PMID: 29424435 DOI: 10.1002/jmv.25043] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/27/2018] [Indexed: 11/09/2022]
Abstract
To evaluate the diagnostic performance of the Sofia influenza A+B fluorescent immunoassay (Sofia FIA), we performed a prospective study at the Chang Gung Memorial Hospital in Taiwan from January 2012 to December 2013. Patients who presented at out-patient clinics or the emergency department with influenza-like illness were included. Upper respiratory tract specimens were collected from oropharynx or nasopharynx. Performance of the Sofia FIA was compared to that of the Formosa One Sure Flu A/B Rapid Test. A Real-time reverse transcriptase-polymerase chain reaction assay (RT-PCR) and/or virus culture were used as reference standards. Of the 109 enrolled patients, the sensitivity, specificity, positive, and negative predictive values of the Sofia FIA to detect influenza A virus were 82%, 89%, 77%, and 89%, respectively. These parameters were 100% when the samples were from nasopharynx. The positive predictive value for influenza B virus detection was 29%. The sensitivity of the Sofia FIA for detection of influenza A virus was 93% between days 2 and 4 after onset of symptoms. For specimens with low viral loads (RT-PCR cycle threshold between 30 and 34.9), the sensitivity of The Sofia FIA was 83% (10/12). The Sofia FIA performed effectively in detecting influenza A virus infection. With nasopharyngeal samples, the performance was comparable to RT-PCR. Although influenza viral load typically decreases with time, the Sofia FIA was sensitive enough to identify influenza infecting patients presenting after several days of illness. However, a high false positive rate limits the assay's usefulness to identify influenza B virus infection.
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Affiliation(s)
- Jeng-How Yang
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
| | - Po-Yen Huang
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
| | - Shian-Sen Shie
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
| | - Shuan Yang
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
| | - Kuo-Chien Tsao
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
| | - Tsu-Lan Wu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
| | - Ting-Shu Wu
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
| | - Ching-Tai Huang
- Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan
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7
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Viruses as Sole Causative Agents of Severe Acute Respiratory Tract Infections in Children. PLoS One 2016; 11:e0150776. [PMID: 26964038 PMCID: PMC4786225 DOI: 10.1371/journal.pone.0150776] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 02/18/2016] [Indexed: 01/02/2023] Open
Abstract
Background Respiratory syncytial virus (RSV) and influenza A viruses are known to cause severe acute respiratory tract infections (SARIs) in children. For other viruses like human rhinoviruses (HRVs) this is less well established. Viral or bacterial co-infections are often considered essential for severe manifestations of these virus infections. Objective The study aims at identifying viruses that may cause SARI in children in the absence of viral and bacterial co-infections, at identifying disease characteristics associated with these single virus infections, and at identifying a possible correlation between viral loads and disease severities. Study Design Between April 2007 and March 2012, we identified children (<18 year) with or without a medical history, admitted to our paediatric intensive care unit (PICU) with SARI or to the medium care (MC) with an acute respiratory tract infection (ARTI) (controls). Data were extracted from the clinical and laboratory databases of our tertiary care paediatric hospital. Patient specimens were tested for fifteen respiratory viruses with real-time reverse transcriptase PCR assays and we selected patients with a single virus infection only. Typical bacterial co-infections were considered unlikely to have contributed to the PICU or MC admission based on C-reactive protein-levels or bacteriological test results if performed. Results We identified 44 patients admitted to PICU with SARI and 40 patients admitted to MC with ARTI. Twelve viruses were associated with SARI, ten of which were also associated with ARTI in the absence of typical bacterial and viral co-infections, with RSV and HRV being the most frequent causes. Viral loads were not different between PICU-SARI patients and MC-ARTI patients. Conclusion Both SARI and ARTI may be caused by single viral pathogens in previously healthy children as well as in children with a medical history. No relationship between viral load and disease severity was identified.
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8
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Transmission of the First Influenza A(H1N1)pdm09 Pandemic Wave in Australia Was Driven by Undetected Infections: Pandemic Response Implications. PLoS One 2015; 10:e0144331. [PMID: 26692335 PMCID: PMC4687009 DOI: 10.1371/journal.pone.0144331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 10/15/2015] [Indexed: 02/03/2023] Open
Abstract
Background During the first wave of influenza A(H1N1)pdm09 in Victoria, Australia the rapid increase in notified cases and the high proportion with relatively mild symptoms suggested that community transmission was established before cases were identified. This lead to the hypothesis that those with low-level infections were the main drivers of the pandemic. Methods A deterministic susceptible-infected-recovered model was constructed to describe the first pandemic wave in a population structured by disease severity levels of asymptomatic, low-level symptoms, moderate symptoms and severe symptoms requiring hospitalisation. The model incorporated mixing, infectivity and duration of infectiousness parameters to calculate subgroup-specific reproduction numbers for each severity level. Results With stratum-specific effective reproduction numbers of 1.82 and 1.32 respectively, those with low-level symptoms, and those with asymptomatic infections were responsible for most of the transmission. The effective reproduction numbers for infections resulting in moderate symptoms and hospitalisation were less than one. Sensitivity analyses confirmed the importance of parameters relating to asymptomatic individuals and those with low-level symptoms. Conclusions Transmission of influenza A(H1N1)pdm09 was largely driven by those invisible to the health system. This has implications for control measures–such as distribution of antivirals to cases and contacts and quarantine/isolation–that rely on detection of infected cases. Pandemic plans need to incorporate milder scenarios, with a graded approach to implementation of control measures.
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9
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Yang JH, Huang PY, Shie SS, Yang S, Tsao KC, Wu TL, Leu HS, Huang CT. Predictive Symptoms and Signs of Laboratory-confirmed Influenza: A Prospective Surveillance Study of Two Metropolitan Areas in Taiwan. Medicine (Baltimore) 2015; 94:e1952. [PMID: 26554802 PMCID: PMC4915903 DOI: 10.1097/md.0000000000001952] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Influenza infection poses annual threats and leads to significant morbidity and mortality. Early diagnosis is the key to successful treatment. Laboratory-based diagnosis has various limitations. Diagnosis based on symptoms or signs is still indispensable in clinical practice. We investigated the symptoms or signs associated with laboratory-confirmed influenza.A prospective study across 2 influenza seasons was performed from June 2010 to June 2012 at 2 branches (Taipei and Lin-Kou) of Chang Gung Memorial Hospital. Patients who visited outpatient clinics with suspected acute respiratory tract infection were sampled by throat swab or nasopharyngeal swab. RT-PCR and/or virus culture were used as a reference standard. We used logistic regression to identify the symptoms or signs associated with laboratory-confirmed influenza infection. We also evaluated the performance metrics of different influenza-like illness used in Taiwan, the USA, and WHO.A total of 158 patients were included in the study. The prevalence of influenza infection was 45% (71/158). Fever, cough, rhinorrhea, sneezing, and nasal congestion were significant predictors for influenza infection. Whereas fever + cough had a best sensitivity (86%; confidence interval [CI] 76%-93%), fever + cough and sneezing had a best specificity (77%; CI 62%-88%). Different case definitions of influenza-like illness had comparable accuracy in sensitivity and specificity.Clinical diagnosis based on symptoms and signs is useful for allocating resources, identifying those who may benefit from early antiviral therapy and providing valuable information for surveillance purpose.
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Affiliation(s)
- Jeng-How Yang
- From the Division of Infectious Diseases, Department of Medicine (J-HY, P-YH, S-SS, H-SL, C-TH); and Department of Laboratory Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan (YS, K-CT, T-LW)
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10
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Huang SSH, Banner D, Paquette SG, Leon AJ, Kelvin AA, Kelvin DJ. Pathogenic influenza B virus in the ferret model establishes lower respiratory tract infection. J Gen Virol 2014; 95:2127-2139. [PMID: 24989173 PMCID: PMC4165929 DOI: 10.1099/vir.0.064352-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Influenza B viruses have become increasingly more prominent during influenza seasons. Influenza B infection is typically considered a mild disease and receives less attention than influenza A, but has been causing 20 to 50 % of the total influenza incidence in several regions around the world. Although there is increasing evidence of mid to lower respiratory tract diseases such as bronchitis and pneumonia in influenza B patients, little is known about the pathogenesis of recent influenza B viruses. Here we investigated the clinical and pathological profiles of infection with strains representing the two current co-circulating B lineages (B/Yamagata and B/Victoria) in the ferret model. Specifically, we studied two B/Victoria (B/Brisbane/60/2008 and B/Bolivia/1526/2010) and two B/Yamagata (B/Florida/04/2006 and B/Wisconsin/01/2010) strain infections in ferrets and observed strain-specific but not lineage-specific pathogenicity. We found B/Brisbane/60/2008 caused the most severe clinical illness and B/Brisbane/60/2008 and the B/Yamagata strains instigated pathology in the middle to lower respiratory tract. Importantly, B/Brisbane/60/2008 established efficient lower respiratory tract infection with high viral burden. Our phylogenetic analyses demonstrate profound reassortment among recent influenza B viruses, which indicates the genetic make-up of B/Brisbane/60/2008 differs from the other strains. This may explain the pathogenicity difference post-infection in ferrets.
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Affiliation(s)
- Stephen S H Huang
- Department of Immunology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Division of Experimental Therapeutics, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - David Banner
- Division of Experimental Therapeutics, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Stephane G Paquette
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Division of Experimental Therapeutics, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Alberto J Leon
- Division of Experimental Therapeutics, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | | | - David J Kelvin
- International Institute of Infection and Immunity, Shantou University Medical College, Shantou, Guangdong, PR China.,Department of Immunology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Division of Experimental Therapeutics, Toronto General Research Institute, University Health Network, Toronto, ON, Canada.,Dipartimento di Scienze Biomediche, Universita' degli Studi di Sassari, Sassari, Sardinia, Italy.,Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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11
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Schuurmans M, Isenring B, Jungo C, Boeni J, Mueller N, Kohler M, Benden C. Clinical features and outcomes of influenza infections in lung transplant recipients: a single-season cohort study. Transpl Infect Dis 2014; 16:430-9. [DOI: 10.1111/tid.12228] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 12/04/2013] [Accepted: 01/27/2014] [Indexed: 01/29/2023]
Affiliation(s)
- M.M. Schuurmans
- Division of Pulmonology; Zurich University Hospital; Zurich Switzerland
| | - B.D. Isenring
- Division of Pulmonology; Zurich University Hospital; Zurich Switzerland
| | - C. Jungo
- Division of Pulmonology; Zurich University Hospital; Zurich Switzerland
| | - J. Boeni
- Institute of Medical Virology; Zurich University; Zurich Switzerland
| | - N.J. Mueller
- Division of Infectious Diseases; Zurich University Hospital; Zurich Switzerland
| | - M. Kohler
- Division of Pulmonology; Zurich University Hospital; Zurich Switzerland
| | - C. Benden
- Division of Pulmonology; Zurich University Hospital; Zurich Switzerland
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12
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Fielding JE, Kelly HA, Mercer GN, Glass K. Systematic review of influenza A(H1N1)pdm09 virus shedding: duration is affected by severity, but not age. Influenza Other Respir Viruses 2013; 8:142-50. [PMID: 24299099 PMCID: PMC4186461 DOI: 10.1111/irv.12216] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2013] [Indexed: 01/02/2023] Open
Abstract
Duration of viral shedding following infection is an important determinant of disease transmission, informing both control policies and disease modelling. We undertook a systematic literature review of the duration of influenza A(H1N1)pdm09 virus shedding to examine the effects of age, severity of illness and receipt of antiviral treatment. Studies were identified by searching the PubMed database using the keywords ‘H1N1’, ‘pandemic’, ‘pandemics’, ‘shed’ and ‘shedding’. Any study of humans with an outcome measure of viral shedding was eligible for inclusion in the review. Comparisons by age, degree of severity and antiviral treatment were made with forest plots. The search returned 214 articles of which 22 were eligible for the review. Significant statistical heterogeneity between studies precluded meta-analysis. The mean duration of viral shedding generally increased with severity of clinical presentation, but we found no evidence of longer shedding duration of influenza A(H1N1)pdm09 among children compared with adults. Shorter viral shedding duration was observed when oseltamivir treatment was administered within 48 hours of illness onset. Considerable differences in the design and analysis of viral shedding studies limit their comparison and highlight the need for a standardised approach. These insights have implications not only for pandemic planning, but also for informing responses and study of seasonal influenza now that the A(H1N1)pdm09 virus has become established as the seasonal H1N1 influenza virus.
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Affiliation(s)
- James E Fielding
- Victorian Infectious Diseases Reference Laboratory, North Melbourne, Vic., Australia; National Centre for Epidemiology and Population Health, The Australian National University, Canberra, ACT, 0200, Australia
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13
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Wang L, Chang LS, Lee IK, Tang KS, Li CC, Eng HL, You HL, Yang KD. Clinical diagnosis of pandemic A(H1N1) 2009 influenza in children with negative rapid influenza diagnostic test by lymphopenia and lower C-reactive protein levels. Influenza Other Respir Viruses 2013; 8:91-8. [PMID: 24373294 PMCID: PMC4177802 DOI: 10.1111/irv.12182] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2013] [Indexed: 01/03/2023] Open
Abstract
Background The sensitivity of rapid influenza diagnostic test (RIDT) of children with influenza-like illness (ILI) remains low. Objective We compare the parameters between pandemic A(H1N1) 2009 influenza with negative RIDT and ILI not H1N1 for improving the low sensitivity of RIDT for children with ILI. Methods In a cohort of consecutive laboratory-confirmed H1N1 influenza, we identified 150 H1N1 children with positive RIDT, 152 H1N1 children with negative RIDT, and 75 children with ILI not H1N1. Viral load in throat, complete blood count (CBC), and C-reactive protein (CRP) levels between H1N1 children with negative RIDT and children with ILI not H1N1 were assessed. Results The diagnostic sensitivity of the RIDT was 45·5%. An analysis of CBC and CRP levels indicated that H1N1 children with negative RIDT had lower total leukocyte, neutrophil, lymphocyte, and basophil counts, and serum CRP levels (P < 0·01). Lymphocyte counts less than 1500 cells/mm3 and CRP levels <15 mg/l, determined by a receiver operating characteristic curve, showed a diagnostic sensitivity of 52·5% and 80·7%, respectively. Combining the lymphocyte counts and CRP levels provided a diagnostic sensitivity of 91·5%. Moreover, H1N1 children with negative RIDT had a lower viral load than those with positive RIDT (3·33 versus 4·48 log10 copies/ml, P < 0·001); the viral load was negatively correlated to the lymphocyte count (P < 0·001). Conclusions A combination of a low lymphocyte count and a low CRP level could, in the early disease phase, provide a useful screening for H1N1 children with false-negative RIDT, potentially facilitating differential diagnoses.
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Affiliation(s)
- Lin Wang
- Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine (KCGMH-CGU), Kaohsiung, Taiwan
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14
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Launes C, Garcia-Garcia JJ, Jordan I, Selva L, Rello J, Muñoz-Almagro C. Viral load at diagnosis and influenza A H1N1 (2009) disease severity in children. Influenza Other Respir Viruses 2012; 6:e89-92. [PMID: 22621401 DOI: 10.1111/j.1750-2659.2012.00383.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
To assess viral load at diagnosis (VLAD) as a biomarker of novel influenza disease severity, epidemiologic and clinical data of admitted patients <18 years old with Influenza A H1N1 (2009) infection and respiratory symptoms were prospectively collected in a single pediatric tertiary hospital, from weeks 30-51 of 2009. Seventy patients were included. VLAD in children who had symptoms for ≥ 5 days was an accurate parameter distinguishing the patients who required mechanical ventilation (MV) from those who did not required it (area under the ROC curve: 0.73; P=0.03). Having <4.5 log10 copies/ml with ≥ 5 days of symptoms was associated with a lower risk of requiring MV.
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Affiliation(s)
- Cristian Launes
- Infectious Diseases Unit, Department of Pediatrics, Hospital Sant Joan de Déu, University of Barcelona, Barcelona, Spain
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