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Respiratory virus transmission dynamics determine timing of asthma exacerbation peaks: Evidence from a population-level model. Proc Natl Acad Sci U S A 2016; 113:2194-9. [PMID: 26858436 DOI: 10.1073/pnas.1518677113] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Asthma exacerbations exhibit a consistent annual pattern, closely mirroring the school calendar. Although respiratory viruses--the "common cold" viruses--are implicated as a principal cause, there is little evidence to link viral prevalence to seasonal differences in risk. We jointly fit a common cold transmission model and a model of biological and environmental exacerbation triggers to estimate effects on hospitalization risk. Asthma hospitalization rate, influenza prevalence, and air quality measures are available, but common cold circulation is not; therefore, we generate estimates of viral prevalence using a transmission model. Our deterministic multivirus transmission model includes transmission rates that vary when school is closed. We jointly fit the two models to 7 y of daily asthma hospitalizations in adults and children (66,000 events) in eight metropolitan areas. For children, we find that daily viral prevalence is the strongest predictor of asthma hospitalizations, with transmission reduced by 45% (95% credible interval =41-49%) during school closures. We detect a transient period of nonspecific immunity between infections lasting 19 (17-21) d. For adults, hospitalizations are more variable, with influenza driving wintertime peaks. Neither particulate matter nor ozone was an important predictor, perhaps because of the large geographic area of the populations. The school calendar clearly and predictably drives seasonal variation in common cold prevalence, which results in the "back-to-school" asthma exacerbation pattern seen in children and indirectly contributes to exacerbation risk in adults. This study provides a framework for anticipating the seasonal dynamics of common colds and the associated risks for asthmatics.
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102
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Pierse N, Kelly H, Thompson MG, Bissielo A, Radke S, Huang QS, Baker MG, Turner N. Influenza vaccine effectiveness for hospital and community patients using control groups with and without non-influenza respiratory viruses detected, Auckland, New Zealand 2014. Vaccine 2015; 34:503-509. [PMID: 26685091 DOI: 10.1016/j.vaccine.2015.11.073] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 11/26/2015] [Accepted: 11/30/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND We aimed to estimate the protection afforded by inactivated influenza vaccine, in both community and hospital settings, in a well characterised urban population in Auckland during 2014. METHODS We used two different comparison groups, all patients who tested negative for influenza and only those patients who tested negative for influenza and had a non-influenza respiratory virus detected, to calculate the vaccine effectiveness in a test negative study design. Estimates were made separately for general practice outpatient consultations and hospitalised patients, stratified by age group and by influenza type and subtype. Vaccine status was confirmed by electronic record for general practice patients and all respiratory viruses were detected by real time polymerase chain reaction. RESULTS 1039 hospitalised and 1154 general practice outpatient consultations met all the study inclusion criteria and had a respiratory sample tested for influenza and other respiratory viruses. Compared to general practice patients, hospitalised patients were more likely to be very young or very old, to be Māori or Pacific Islander, to have a low income and to suffer from chronic disease. Vaccine effectiveness (VE) adjusted for age and other participant characteristics using all influenza negative controls was 42% (95% CI: 16 to 60%) for hospitalised and 56% (95% CI: 35 to 70%) for general practice patients. The vaccine appeared to be most effective against the influenza A(H1N1)pdm09 strain with an adjusted VE of 62% (95% CI:38 to 77%) for hospitalised and 59% (95% CI:36 to 74%) for general practice patients, using influenza virus negative controls. Similar results found when patients testing positive for a non-influenza respiratory virus were used as the control group. CONCLUSION This study contributes to validation of the test negative design and confirms that inactivated influenza vaccines continue to provide modest but significant protection against laboratory-confirmed influenza.
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Affiliation(s)
- Nevil Pierse
- The University of Otago, Wellington, PO Box 7343, Wellington South 6242, New Zealand.
| | - Heath Kelly
- The Australian National University, Canberra 0200, ACT Australia; Victorian Infectious Diseases Reference Laboratory, Melbourne, VIC, Australia.
| | - Mark G Thompson
- Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
| | - Ange Bissielo
- Institute of Environmental Science and Research, Upper Hutt Wellington, New Zealand.
| | - Sarah Radke
- The University of Auckland, Private Bag 92019, Victoria St West, Auckland, New Zealand.
| | - Q Sue Huang
- Institute of Environmental Science and Research, Upper Hutt Wellington, New Zealand.
| | - Michael G Baker
- The University of Otago, Wellington, PO Box 7343, Wellington South 6242, New Zealand.
| | - Nikki Turner
- The University of Auckland, Private Bag 92019, Victoria St West, Auckland, New Zealand.
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103
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Laurie KL, Guarnaccia TA, Carolan LA, Yan AWC, Aban M, Petrie S, Cao P, Heffernan JM, McVernon J, Mosse J, Kelso A, McCaw JM, Barr IG. Interval Between Infections and Viral Hierarchy Are Determinants of Viral Interference Following Influenza Virus Infection in a Ferret Model. J Infect Dis 2015; 212:1701-10. [PMID: 25943206 PMCID: PMC4633756 DOI: 10.1093/infdis/jiv260] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 03/23/2015] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Epidemiological studies suggest that, following infection with influenza virus, there is a short period during which a host experiences a lower susceptibility to infection with other influenza viruses. This viral interference appears to be independent of any antigenic similarities between the viruses. We used the ferret model of human influenza to systematically investigate viral interference. METHODS Ferrets were first infected then challenged 1-14 days later with pairs of influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses circulating in 2009 and 2010. RESULTS Viral interference was observed when the interval between initiation of primary infection and subsequent challenge was <1 week. This effect was virus specific and occurred between antigenically related and unrelated viruses. Coinfections occurred when 1 or 3 days separated infections. Ongoing shedding from the primary virus infection was associated with viral interference after the secondary challenge. CONCLUSIONS The interval between infections and the sequential combination of viruses were important determinants of viral interference. The influenza viruses in this study appear to have an ordered hierarchy according to their ability to block or delay infection, which may contribute to the dominance of different viruses often seen in an influenza season.
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Affiliation(s)
- Karen L. Laurie
- WHO Collaborating Centre for Reference and Research on Influenza, Victorian Infectious Diseases Reference Laboratory at the Peter Doherty Institute for Infection and Immunity
- School of Applied and Biomedical Sciences, Federation University, Churchill, Australia
| | - Teagan A. Guarnaccia
- WHO Collaborating Centre for Reference and Research on Influenza, Victorian Infectious Diseases Reference Laboratory at the Peter Doherty Institute for Infection and Immunity
- School of Applied and Biomedical Sciences, Federation University, Churchill, Australia
| | - Louise A. Carolan
- WHO Collaborating Centre for Reference and Research on Influenza, Victorian Infectious Diseases Reference Laboratory at the Peter Doherty Institute for Infection and Immunity
| | - Ada W. C. Yan
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne
| | - Malet Aban
- WHO Collaborating Centre for Reference and Research on Influenza, Victorian Infectious Diseases Reference Laboratory at the Peter Doherty Institute for Infection and Immunity
| | - Stephen Petrie
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne
| | - Pengxing Cao
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne
| | - Jane M. Heffernan
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne
- Modelling Infection and Immunity Laboratory, Centre for Disease Modelling, York Institute for Health Research
- Program in Mathematics and Statistics, York University, Toronto, Canada
| | - Jodie McVernon
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne
- Modelling and Simulation Research Group, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne
| | - Jennifer Mosse
- School of Applied and Biomedical Sciences, Federation University, Churchill, Australia
| | - Anne Kelso
- WHO Collaborating Centre for Reference and Research on Influenza, Victorian Infectious Diseases Reference Laboratory at the Peter Doherty Institute for Infection and Immunity
| | - James M. McCaw
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne
- Modelling and Simulation Research Group, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne
| | - Ian G. Barr
- WHO Collaborating Centre for Reference and Research on Influenza, Victorian Infectious Diseases Reference Laboratory at the Peter Doherty Institute for Infection and Immunity
- School of Applied and Biomedical Sciences, Federation University, Churchill, Australia
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104
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Grijalva CG, Zhu Y, Williams DJ, Self WH, Ampofo K, Pavia AT, Stockmann CR, McCullers J, Arnold SR, Wunderink RG, Anderson EJ, Lindstrom S, Fry AM, Foppa IM, Finelli L, Bramley AM, Jain S, Griffin MR, Edwards KM. Association Between Hospitalization With Community-Acquired Laboratory-Confirmed Influenza Pneumonia and Prior Receipt of Influenza Vaccination. JAMA 2015; 314:1488-97. [PMID: 26436611 PMCID: PMC4688454 DOI: 10.1001/jama.2015.12160] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
IMPORTANCE Few studies have evaluated the relationship between influenza vaccination and pneumonia, a serious complication of influenza infection. OBJECTIVE To assess the association between influenza vaccination status and hospitalization for community-acquired laboratory-confirmed influenza pneumonia. DESIGN, SETTING, AND PARTICIPANTS The Etiology of Pneumonia in the Community (EPIC) study was a prospective observational multicenter study of hospitalizations for community-acquired pneumonia conducted from January 2010 through June 2012 at 4 US sites. In this case-control study, we used EPIC data from patients 6 months or older with laboratory-confirmed influenza infection and verified vaccination status during the influenza seasons and excluded patients with recent hospitalization, from chronic care residential facilities, and with severe immunosuppression. Logistic regression was used to calculate odds ratios, comparing the odds of vaccination between influenza-positive (case) and influenza-negative (control) patients with pneumonia, controlling for demographics, comorbidities, season, study site, and timing of disease onset. Vaccine effectiveness was estimated as (1 - adjusted odds ratio) × 100%. EXPOSURE Influenza vaccination, verified through record review. MAIN OUTCOMES AND MEASURES Influenza pneumonia, confirmed by real-time reverse-transcription polymerase chain reaction performed on nasal/oropharyngeal swabs. RESULTS Overall, 2767 patients hospitalized for pneumonia were eligible for the study; 162 (5.9%) had laboratory-confirmed influenza. Twenty-eight of 162 cases (17%) with influenza-associated pneumonia and 766 of 2605 controls (29%) with influenza-negative pneumonia had been vaccinated. The adjusted odds ratio of prior influenza vaccination between cases and controls was 0.43 (95% CI, 0.28-0.68; estimated vaccine effectiveness, 56.7%; 95% CI, 31.9%-72.5%). CONCLUSIONS AND RELEVANCE Among children and adults hospitalized with community-acquired pneumonia, those with laboratory-confirmed influenza-associated pneumonia, compared with those with pneumonia not associated with influenza, had lower odds of having received influenza vaccination.
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Affiliation(s)
- Carlos G. Grijalva
- Vanderbilt University School of Medicine, Nashville, TN, USA
- Geriatric Research Education Clinical Center (GRECC), VA Tennessee Valley, Nashville, TN, USA
| | - Yuwei Zhu
- Vanderbilt University School of Medicine, Nashville, TN, USA
| | | | - Wesley H. Self
- Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Krow Ampofo
- University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Andrew T. Pavia
- University of Utah School of Medicine, Salt Lake City, UT, USA
| | | | | | | | | | | | | | - Alicia M. Fry
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Ivo M. Foppa
- Centers for Disease Control and Prevention, Atlanta, GA, USA
- Battelle, Atlanta, GA, USA
| | - Lyn Finelli
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Anna M. Bramley
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Seema Jain
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Marie R. Griffin
- Vanderbilt University School of Medicine, Nashville, TN, USA
- Geriatric Research Education Clinical Center (GRECC), VA Tennessee Valley, Nashville, TN, USA
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105
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Rhedin S, Lindstrand A, Hjelmgren A, Ryd-Rinder M, Öhrmalm L, Tolfvenstam T, Örtqvist Å, Rotzén-Östlund M, Zweygberg-Wirgart B, Henriques-Normark B, Broliden K, Naucler P. Respiratory viruses associated with community-acquired pneumonia in children: matched case-control study. Thorax 2015; 70:847-53. [PMID: 26077969 DOI: 10.1136/thoraxjnl-2015-206933] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 05/25/2015] [Indexed: 01/12/2023]
Abstract
BACKGROUND Community-acquired pneumonia (CAP) is the leading cause of death in children worldwide and a substantial proportion of childhood CAP is caused by viruses. A better understanding of the role of virus infections in this condition is needed to improve clinical management and preventive measures. The aim of the study was therefore to assess the association between specific respiratory viruses and childhood CAP. METHODS A case-control study was conducted during 3 years in Stockholm, Sweden. Cases were children aged ≤5 years with radiological CAP. Healthy controls were consecutively enrolled at child health units during routine visits and matched to cases on age and calendar time. Nasopharyngeal aspirates were obtained and analysed by real-time PCR for 15 viruses. Multivariate conditional logistic regression was used to account for coinfections with other viruses and baseline characteristics. RESULTS A total of 121 cases, of which 93 cases met the WHO criteria for radiological pneumonia, and 240 controls were included in the study. Viruses were detected in 81% of the cases (n=98) and 56% of the controls (n=134). Influenza virus, metapneumovirus and respiratory syncytial virus were detected in 60% of cases and were significantly associated with CAP with ORs >10. There was no association with parainfluenza virus, human enterovirus or rhinovirus and coronavirus and bocavirus were negatively associated with CAP. CONCLUSIONS Our study indicates viral CAP is an underestimated disease and points out hMPV as a new important target for the prevention of childhood CAP.
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Affiliation(s)
- Samuel Rhedin
- Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Ann Lindstrand
- The Public Health Agency of Sweden, Stockholm, Sweden Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
| | - Annie Hjelmgren
- Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Malin Ryd-Rinder
- Department of Clinical Science and Education, Karolinska Institutet, Sachs' Children and Youth Hospital, South General Hospital, Stockholm, Sweden
| | - Lars Öhrmalm
- Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Thomas Tolfvenstam
- Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden The Public Health Agency of Sweden, Stockholm, Sweden
| | - Åke Örtqvist
- Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden Department of Communicable Disease and Control, Stockholm County Council, Stockholm, Sweden
| | - Maria Rotzén-Östlund
- Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Benita Zweygberg-Wirgart
- Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Birgitta Henriques-Normark
- Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Kristina Broliden
- Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Pontus Naucler
- Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
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106
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Meeyai A, Praditsitthikorn N, Kotirum S, Kulpeng W, Putthasri W, Cooper BS, Teerawattananon Y. Seasonal influenza vaccination for children in Thailand: a cost-effectiveness analysis. PLoS Med 2015; 12:e1001829; discussion e1001829. [PMID: 26011712 PMCID: PMC4444096 DOI: 10.1371/journal.pmed.1001829] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 04/13/2015] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Seasonal influenza is a major cause of mortality worldwide. Routine immunization of children has the potential to reduce this mortality through both direct and indirect protection, but has not been adopted by any low- or middle-income countries. We developed a framework to evaluate the cost-effectiveness of influenza vaccination policies in developing countries and used it to consider annual vaccination of school- and preschool-aged children with either trivalent inactivated influenza vaccine (TIV) or trivalent live-attenuated influenza vaccine (LAIV) in Thailand. We also compared these approaches with a policy of expanding TIV coverage in the elderly. METHODS AND FINDINGS We developed an age-structured model to evaluate the cost-effectiveness of eight vaccination policies parameterized using country-level data from Thailand. For policies using LAIV, we considered five different age groups of children to vaccinate. We adopted a Bayesian evidence-synthesis framework, expressing uncertainty in parameters through probability distributions derived by fitting the model to prospectively collected laboratory-confirmed influenza data from 2005-2009, by meta-analysis of clinical trial data, and by using prior probability distributions derived from literature review and elicitation of expert opinion. We performed sensitivity analyses using alternative assumptions about prior immunity, contact patterns between age groups, the proportion of infections that are symptomatic, cost per unit vaccine, and vaccine effectiveness. Vaccination of children with LAIV was found to be highly cost-effective, with incremental cost-effectiveness ratios between about 2,000 and 5,000 international dollars per disability-adjusted life year averted, and was consistently preferred to TIV-based policies. These findings were robust to extensive sensitivity analyses. The optimal age group to vaccinate with LAIV, however, was sensitive both to the willingness to pay for health benefits and to assumptions about contact patterns between age groups. CONCLUSIONS Vaccinating school-aged children with LAIV is likely to be cost-effective in Thailand in the short term, though the long-term consequences of such a policy cannot be reliably predicted given current knowledge of influenza epidemiology and immunology. Our work provides a coherent framework that can be used for similar analyses in other low- and middle-income countries.
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Affiliation(s)
- Aronrag Meeyai
- Health Intervention and Technology Assessment Program, Nonthaburi, Thailand
- Department of Epidemiology, Faculty of Public Health, Mahidol University, Bangkok, Thailand
| | - Naiyana Praditsitthikorn
- Health Intervention and Technology Assessment Program, Nonthaburi, Thailand
- Bureau of AIDS, TB, and STI, Department of Disease Control, Ministry of Public Health, Nonthaburi, Thailand
| | - Surachai Kotirum
- Health Intervention and Technology Assessment Program, Nonthaburi, Thailand
| | - Wantanee Kulpeng
- Health Intervention and Technology Assessment Program, Nonthaburi, Thailand
| | - Weerasak Putthasri
- International Health Policy Program, Ministry of Public Health, Nonthaburi, Thailand
| | - Ben S. Cooper
- Mahidol Oxford Tropical Medicine Research Unit, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
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107
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Yang L, Chan KH, Suen LKP, Chan KP, Wang X, Cao P, He D, Peiris JSM, Wong CM. Impact of the 2009 H1N1 Pandemic on Age-Specific Epidemic Curves of Other Respiratory Viruses: A Comparison of Pre-Pandemic, Pandemic and Post-Pandemic Periods in a Subtropical City. PLoS One 2015; 10:e0125447. [PMID: 25928217 PMCID: PMC4416050 DOI: 10.1371/journal.pone.0125447] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 03/23/2015] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The 2009 H1N1 influenza pandemic caused offseason peaks in temperate regions but coincided with the summer epidemic of seasonal influenza and other common respiratory viruses in subtropical Hong Kong. This study was aimed to investigate the impact of the pandemic on age-specific epidemic curves of other respiratory viruses. METHODS Weekly laboratory-confirmed cases of influenza A (subtypes seasonal A(H1N1), A(H3N2), pandemic virus A(H1N1)pdm09), influenza B, respiratory syncytial virus (RSV), adenovirus and parainfluenza were obtained from 2004 to 2013. Age-specific epidemic curves of viruses other than A(H1N1)pdm09 were compared between the pre-pandemic (May 2004-April 2009), pandemic (May 2009-April 2010) and post-pandemic periods (May 2010-April 2013). RESULTS There were two peaks of A(H1N1)pdm09 in Hong Kong, the first in September 2009 and the second in February 2011. The infection rate was found highest in young children in both waves, but markedly fewer cases in school children were recorded in the second wave than in the first wave. Positive proportions of viruses other than A(H1N1)pdm09 markedly decreased in all age groups during the first pandemic wave. After the first wave of the pandemic, the positive proportion of A(H3N2) increased, but those of B and RSV remained slightly lower than their pre-pandemic proportions. Changes in seasonal pattern and epidemic peak time were also observed, but inconsistent across virus-age groups. CONCLUSION Our findings provide some evidence that age distribution, seasonal pattern and peak time of other respiratory viruses have changed since the pandemic. These changes could be the result of immune interference and changing health seeking behavior, but the mechanism behind still needs further investigations.
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Affiliation(s)
- Lin Yang
- School of Nursing, The Hong Kong Polytechnic University, Hong Kong
- * E-mail: (CMW); (LY)
| | - Kwok Hung Chan
- Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Lorna K. P. Suen
- School of Nursing, The Hong Kong Polytechnic University, Hong Kong
| | - King Pan Chan
- Division of Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong
| | - Xiling Wang
- Division of Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong
| | - Peihua Cao
- Division of Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong
| | - Daihai He
- Department of Applied Mathematics, The Hong Kong Polytechnic University, Hong Kong
| | - J. S. Malik Peiris
- State Key Laboratory of Emerging Infectious Disease, School of Public Health, The University of Hong Kong, Hong Kong
| | - Chit Ming Wong
- Division of Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong
- * E-mail: (CMW); (LY)
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108
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Potential effect of virus interference on influenza vaccine effectiveness estimates in test-negative designs. Epidemiol Infect 2015; 142:2642-6. [PMID: 25372226 DOI: 10.1017/s0950268814000107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A hypothetical influenza infection-induced non-specific immunity may reduce the risk of subsequent non-influenza respiratory virus (NIRV) infection and bias the influenza vaccine effectiveness (VE) estimates in test-negative designs (TNDs). We conducted a simulation study using a simple TND model and explored the degree of bias in the VE estimates. The bias was marginal during the usual seasons and most of the time during pandemics; the bias only became large when the influenza infection attack rate increased to pandemic levels (>50%), the true VE was low to moderate, and the non-specific immunity almost completely protected from NIRV infections and lasted at least half the influenza season.
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109
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Abstract
Host immunity is a major driver of pathogen evolution and thus a major determinant of pathogen diversity. Explanations for pathogen diversity traditionally assume simple interactions between pathogens and the immune system, a view encapsulated by the susceptible-infected-recovered (SIR) model. However, there is growing evidence that the complexity of many host-pathogen interactions is dynamically important. This revised perspective requires broadening the definition of a pathogen's immunological phenotype, or what can be thought of as its immunological niche. After reviewing evidence that interactions between pathogens and host immunity drive much of pathogen evolution, I introduce the concept of a pathogen's immunological phenotype. Models that depart from the SIR paradigm demonstrate the utility of this perspective and show that it is particularly useful in understanding vaccine-induced evolution. This paper highlights questions in immunology, evolution, and ecology that must be answered to advance theories of pathogen diversity.
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Affiliation(s)
- Sarah Cobey
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois
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110
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Influenza vaccine effectiveness estimates for Western Australia during a period of vaccine and virus strain stability, 2010 to 2012. Vaccine 2014; 32:6312-8. [PMID: 25223268 DOI: 10.1016/j.vaccine.2014.08.066] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 07/04/2014] [Accepted: 08/27/2014] [Indexed: 11/22/2022]
Abstract
During 2010-2012 the strain composition of the influenza vaccine in the Southern Hemisphere did not change, but the circulating virus type/subtype did. We pooled data for these years from the Western Australian sentinel medical practice surveillance system for influenza to estimate vaccine effectiveness (VE) by influenza virus type and subtype. A case test-negative design was used with VE estimated as (1-odds ratio)×100%. There were 2182 patients included in the analysis across the 3 years studied. The predominant subtype was A/H1pdm09 in 2010 and 2011, and A/H3 in 2012. The overall adjusted VE estimate against all influenza for 2010-2012 was 51% (95% CI: 36, 63). Estimates were highest against A/H1pdm09 at 74% (95% CI: 47, 87), followed by 56% (95% CI: 33, 71) for influenza B and lowest against A/H3 at 39% (95% CI: 13, 57). When analyses were restricted to compare influenza-positive patients with patients who tested positive for a non-influenza virus, overall adjusted VE was 59% (95% CI: 39, 72). These results suggest moderate protection against influenza by vaccination in Western Australia over the period 2010-2012, and are consistent with findings from other settings.
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111
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Cowling BJ, Chan KH, Feng S, Chan ELY, Lo JYC, Peiris JSM, Chiu SS. The effectiveness of influenza vaccination in preventing hospitalizations in children in Hong Kong, 2009-2013. Vaccine 2014; 32:5278-84. [PMID: 25092636 PMCID: PMC4165553 DOI: 10.1016/j.vaccine.2014.07.084] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/11/2014] [Accepted: 07/22/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Influenza vaccination is widely recommended every year to protect individuals against influenza virus infection and illness. There are few published estimates of influenza vaccine effectiveness against hospitalization in children or from subtropical regions. METHODS We conducted a test-negative year-round study between October 2009 and September 2013, recruiting children 6 months to 17 years of age admitted to two hospitals in Hong Kong with a febrile acute respiratory infection. Cases were tested for influenza A and B and conditional logistic regression was used to estimate vaccine effectiveness comparing influenza vaccination history of the trivalent influenza vaccine (TIV) among patients testing positive versus negative for influenza, adjusting for age and sex and matching by calendar week of recruitment. RESULTS Overall vaccine effectiveness against hospitalization with laboratory-confirmed influenza A and B was estimated to be 61.7% (95% CI: 43.0%, 74.2%). The estimated vaccine effectiveness against A(H3N2) was 36.6% (95% CI: -25.5%, 67.9%) compared to 71.5% (95% CI: 39.4%, 86.6%) for A(H1N1)pdm09 and 68.8% (95% CI: 41.6%, 83.3%) for B. CONCLUSIONS Vaccine effectiveness against hospitalization in children varied from year to year, but was moderate to high overall even in an area with influenza activity throughout the year.
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Affiliation(s)
- Benjamin J Cowling
- Division of Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Kwok-Hung Chan
- Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Shuo Feng
- Division of Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Eunice L Y Chan
- Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Janice Y C Lo
- Public Health Laboratory Services Branch, Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region, China
| | - J S Malik Peiris
- Division of Public Health Laboratory Sciences, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China; Centre for Influenza Research, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Susan S Chiu
- Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
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A probability model for evaluating the bias and precision of influenza vaccine effectiveness estimates from case-control studies. Epidemiol Infect 2014; 143:1417-26. [PMID: 25147970 DOI: 10.1017/s0950268814002179] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
As influenza vaccination is now widely recommended, randomized clinical trials are no longer ethical in many populations. Therefore, observational studies on patients seeking medical care for acute respiratory illnesses (ARIs) are a popular option for estimating influenza vaccine effectiveness (VE). We developed a probability model for evaluating and comparing bias and precision of estimates of VE against symptomatic influenza from two commonly used case-control study designs: the test-negative design and the traditional case-control design. We show that when vaccination does not affect the probability of developing non-influenza ARI then VE estimates from test-negative design studies are unbiased even if vaccinees and non-vaccinees have different probabilities of seeking medical care against ARI, as long as the ratio of these probabilities is the same for illnesses resulting from influenza and non-influenza infections. Our numerical results suggest that in general, estimates from the test-negative design have smaller bias compared to estimates from the traditional case-control design as long as the probability of non-influenza ARI is similar among vaccinated and unvaccinated individuals. We did not find consistent differences between the standard errors of the estimates from the two study designs.
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113
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Nunes B, Machado A, Guiomar R, Pechirra P, Conde P, Cristovão P, Falcão I. Estimates of 2012/13 influenza vaccine effectiveness using the case test-negative control design with different influenza negative control groups. Vaccine 2014; 32:4443-4449. [PMID: 24962756 DOI: 10.1016/j.vaccine.2014.06.053] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 05/22/2014] [Accepted: 06/11/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND In recent years several reports of influenza vaccine effectiveness (VE) have been made early for public health decision. The majority of these studies use the case test-negative control design (TND), which has been showed to provide, under certain conditions, unbiased estimates of influenza VE. Nevertheless, discussions have been taken on the best influenza negative control group to use. The present study aims to contribute to the knowledge on this field by comparing influenza VE estimates using three test-negative controls: all influenza negative, non-influenza respiratory virus and pan-negative. METHODS Incident ILI patients were prospectively selected and swabbed by a sample of general practitioners. Cases were ILI patients tested positive for influenza and controls ILI patients tested negative for influenza. The influenza negative control group was divided into non-influenza virus control group and pan-negative control group. Data were collected on vaccination status and confounding factors. Influenza VE was estimated as one minus the odds ratio of been vaccinated in cases versus controls adjusted for confounding effect by logistic regression. RESULTS Confounder adjusted influenza VE against medically attended laboratory-confirmed influenza was 68.4% (95% CI: 20.7-87.4%) using all influenza negatives controls, 82.1% (95% CI: 47.6-93.9%) using non-influenza controls and 49.4% (95% CI: -44.7% to 82.3%) using pan-negative controls. CONCLUSIONS Influenza VE estimates differed according to the influenza negative control group used. These results are in accordance with the expected under the hypothesis of differential viral interference between influenza vaccinated and unvaccinated individuals. Given the wide importance of TND study further studies should be conducted in order to clarify the observed differences.
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Affiliation(s)
- Baltazar Nunes
- Unidade de Investigação Epidemiológica, Departamento de Epidemiologia, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal.
| | - Ausenda Machado
- Unidade de Investigação Epidemiológica, Departamento de Epidemiologia, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Raquel Guiomar
- Laboratório Nacional de Referência para o Vírus da Gripe, Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Pedro Pechirra
- Laboratório Nacional de Referência para o Vírus da Gripe, Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Patrícia Conde
- Laboratório Nacional de Referência para o Vírus da Gripe, Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Paula Cristovão
- Laboratório Nacional de Referência para o Vírus da Gripe, Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Isabel Falcão
- Unidade de Apoio às Emergências em Saúde Pública, Direção Geral da Saúde, Lisboa, Portugal
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Hayward AC, Fragaszy EB, Bermingham A, Wang L, Copas A, Edmunds WJ, Ferguson N, Goonetilleke N, Harvey G, Kovar J, Lim MSC, McMichael A, Millett ERC, Nguyen-Van-Tam JS, Nazareth I, Pebody R, Tabassum F, Watson JM, Wurie FB, Johnson AM, Zambon M. Comparative community burden and severity of seasonal and pandemic influenza: results of the Flu Watch cohort study. THE LANCET. RESPIRATORY MEDICINE 2014; 2:445-54. [PMID: 24717637 PMCID: PMC7164821 DOI: 10.1016/s2213-2600(14)70034-7] [Citation(s) in RCA: 278] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Assessment of the effect of influenza on populations, including risk of infection, illness if infected, illness severity, and consultation rates, is essential to inform future control and prevention. We aimed to compare the community burden and severity of seasonal and pandemic influenza across different age groups and study years and gain insight into the extent to which traditional surveillance underestimates this burden. METHODS Using preseason and postseason serology, weekly illness reporting, and RT-PCR identification of influenza from nasal swabs, we tracked the course of seasonal and pandemic influenza over five successive cohorts (England 2006-11; 5448 person-seasons' follow-up). We compared burden and severity of seasonal and pandemic strains. We weighted analyses to the age and regional structure of England to give nationally representative estimates. We compared symptom profiles over the first week of illness for different strains of PCR-confirmed influenza and non-influenza viruses using ordinal logistic regression with symptom severity grade as the outcome variable. FINDINGS Based on four-fold titre rises in strain-specific serology, on average influenza infected 18% (95% CI 16-22) of unvaccinated people each winter. Of those infected there were 69 respiratory illnesses per 100 person-influenza-seasons compared with 44 per 100 in those not infected with influenza. The age-adjusted attributable rate of illness if infected was 23 illnesses per 100 person-seasons (13-34), suggesting most influenza infections are asymptomatic. 25% (18-35) of all people with serologically confirmed infections had PCR-confirmed disease. 17% (10-26) of people with PCR-confirmed influenza had medically attended illness. These figures did not differ significantly when comparing pandemic with seasonal influenza. Of PCR-confirmed cases, people infected with the 2009 pandemic strain had markedly less severe symptoms than those infected with seasonal H3N2. INTERPRETATION Seasonal influenza and the 2009 pandemic strain were characterised by similar high rates of mainly asymptomatic infection with most symptomatic cases self-managing without medical consultation. In the community the 2009 pandemic strain caused milder symptoms than seasonal H3N2. FUNDING Medical Research Council and the Wellcome Trust.
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Affiliation(s)
- Andrew C Hayward
- UCL Research Department of Infection and Population Health, University College London, London, UK.
| | - Ellen B Fragaszy
- UCL Research Department of Infection and Population Health, University College London, London, UK; Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | | | - Lili Wang
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Andrew Copas
- UCL Research Department of Infection and Population Health, University College London, London, UK
| | - W John Edmunds
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Neil Ferguson
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Nilu Goonetilleke
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK; Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gabrielle Harvey
- UCL Research Department of Infection and Population Health, University College London, London, UK
| | - Jana Kovar
- UCL Research Department of Infection and Population Health, University College London, London, UK
| | - Megan S C Lim
- UCL Research Department of Infection and Population Health, University College London, London, UK; Centre for Population Health, Burnet Institute, Melbourne, VIC, Australia
| | - Andrew McMichael
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Elizabeth R C Millett
- UCL Research Department of Infection and Population Health, University College London, London, UK; Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Jonathan S Nguyen-Van-Tam
- Health Protection and Influenza Research Group, Division of Epidemiology and Public Health, University of Nottingham, Nottingham, UK
| | - Irwin Nazareth
- UCL Department of Primary Care and Population Health, University College London, London, UK
| | - Richard Pebody
- Respiratory Diseases Department, Public Health England, Colindale, UK
| | - Faiza Tabassum
- UCL Research Department of Infection and Population Health, University College London, London, UK
| | - John M Watson
- Respiratory Diseases Department, Public Health England, Colindale, UK
| | - Fatima B Wurie
- UCL Research Department of Infection and Population Health, University College London, London, UK
| | - Anne M Johnson
- UCL Research Department of Infection and Population Health, University College London, London, UK
| | - Maria Zambon
- Respiratory Virus Unit, Public Health England, Colindale, UK
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115
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Sundaram ME, McClure DL, VanWormer JJ, Friedrich TC, Meece JK, Belongia EA. Influenza vaccination is not associated with detection of noninfluenza respiratory viruses in seasonal studies of influenza vaccine effectiveness. Clin Infect Dis 2014; 57:789-93. [PMID: 23748138 PMCID: PMC7107973 DOI: 10.1093/cid/cit379] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The test-negative control study design is the basis for observational studies of influenza vaccine effectiveness (VE). Recent studies have suggested that influenza vaccination increases the risk of noninfluenza respiratory virus infection. Such an effect could create bias in VE studies using influenza-negative controls. We investigated the association between influenza infection, vaccination, and detection of other respiratory viruses among children <5 years old and adults ≥50 years old with acute respiratory illness who participated in seasonal studies of influenza vaccine effectiveness. METHODS Nasal/nasopharyngeal samples collected from 2004–2005 through 2009–2010 were tested for 19 respiratory virus targets using a multiplex reverse-transcription polymerase chain reaction (RT-PCR) platform. Vaccination status was determined using a validated registry. Adjusted odds ratios for influenza and vaccination status were calculated using three different control groups: influenza-negative, other respiratory virus positive, and pan-negative. RESULTS Influenza was detected in 12% of 2010 children and 20% of 1738 adults. Noninfluenza respiratory viruses were detected in 70% of children and 38% of adults without influenza. The proportion vaccinated did not vary between virus-positive controls and pan-negative controls in children (P = .62) or adults (P = .33). Influenza infection was associated with reduced odds of vaccination, but adjusted odds ratios differed by no more than 0.02 when the analysis used influenza-negative or virus-positive controls. CONCLUSIONS Influenza vaccination was not associated with detection of noninfluenza respiratory viruses. Use of influenza-negative controls did not generate a biased estimate of vaccine effectiveness due to an effect of vaccination on other respiratory virus infections.
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Affiliation(s)
- Maria E Sundaram
- Marshfield Clinic Research Foundation, Marshfield, WI 54449, USA
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116
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Blyth CC, Jacoby P, Effler PV, Kelly H, Smith DW, Robins C, Willis GA, Levy A, Keil AD, Richmond PC. Effectiveness of trivalent flu vaccine in healthy young children. Pediatrics 2014; 133:e1218-25. [PMID: 24753525 DOI: 10.1542/peds.2013-3707] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND There are few studies evaluating the effectiveness of trivalent influenza vaccination (TIV) in young children, particularly in children <2 years. The Western Australian Influenza Vaccine Effectiveness Study commenced in 2008 to evaluate a program providing TIV to children aged 6 to 59 months. METHODS An observational study enrolling children with influenza-like illness presenting to a tertiary pediatric hospital was conducted (2008-2012). Vaccination status was determined by parental questionnaire and confirmed via the national immunization register and/or vaccine providers. Respiratory virus polymerase chain reaction and culture were performed on nasopharyngeal samples. The test-negative design was used to estimate vaccine effectiveness (VE) by using 2 control groups: all influenza test-negative subjects and other-virus-detected (OVD) subjects. Adjusted odds ratios were estimated from models with season, month of disease onset, age, gender, indigenous status, prematurity, and comorbidities as covariates. Subjects enrolled in 2009 were excluded from VE calculations. RESULTS Of 2001 children enrolled, influenza was identified in 389 (20.4%) children. Another respiratory virus was identified in 1134 (59.6%) children. Overall, 295 of 1903 (15.5%) children were fully vaccinated and 161 of 1903 (8.4%) children were partially vaccinated. Vaccine uptake was significantly lower in 2010-2012 after increased febrile adverse events observed in 2010. Using test-negative controls, VE was 64.7% (95% confidence interval [CI]: 33.7%-81.2%). No difference in VE was observed with OVD controls (65.8%; 95% CI: 32.1%-82.8%). The VE for children <2 years was 85.8% (95% CI: 37.9%-96.7%). CONCLUSIONS This study reveals the effectiveness of TIV in young children over 4 seasons by using test-negative and OVD controls. TIV was effective in children aged <2 years. Despite demonstrated vaccine effectiveness, uptake of TIV remains suboptimal.
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Affiliation(s)
- Christopher C Blyth
- School of Paediatrics and Child Health and Princess Margaret Hospital for Children, Perth, Australia; Telethon Institute of Child Health Research, West Perth, Australia; PathWest Laboratory Medicine, Nedlands, Australia;
| | - Peter Jacoby
- Telethon Institute of Child Health Research, West Perth, Australia
| | - Paul V Effler
- Communicable Disease Control Directorate, Department of Health, Perth, Australia
| | - Heath Kelly
- Victorian Infectious Diseases Reference Laboratory, Melbourne, Australia; and Australian National University, Australian Capital Territory, Australia
| | - David W Smith
- PathWest Laboratory Medicine, Nedlands, Australia; School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Australia
| | - Christine Robins
- Telethon Institute of Child Health Research, West Perth, Australia
| | | | - Avram Levy
- PathWest Laboratory Medicine, Nedlands, Australia
| | | | - Peter C Richmond
- School of Paediatrics and Child Health and Princess Margaret Hospital for Children, Perth, Australia; Telethon Institute of Child Health Research, West Perth, Australia
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117
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Vaccine effectiveness against medically attended laboratory-confirmed influenza in Japan, 2011-2012 Season. PLoS One 2014; 9:e88813. [PMID: 24551167 PMCID: PMC3923823 DOI: 10.1371/journal.pone.0088813] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/16/2014] [Indexed: 11/19/2022] Open
Abstract
The objective of this study was to estimate influenza vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza during the 2011-2012 season in Japan using a test-negative case-control study design. The effect of co-circulating non-influenza respiratory viruses (NIRVs) on VE estimates was also explored. Nasopharyngeal swab samples were collected from outpatients with influenza-like illnesses (ILIs) in a community hospital in Nagasaki, Japan. Thirteen respiratory viruses (RVs), including influenza A and B, were identified from the samples using a multiplex polymerase chain reaction. The difference in VE point estimates was assessed using three different controls: ILI patients that tested negative for influenza, those that tested negative for all RVs, and those that tested positive for NIRVs. The adjusted VE against medically attended, laboratory-confirmed influenza using all influenza-negative controls was 5.3% (95% confidence interval [CI], -60.5 to 44.1). The adjusted VEs using RV-negative and NIRV-positive controls were -1.5% (95% CI, -74.7 to 41) and 50% (95% CI, -43.2 to 82.5), respectively. Influenza VE was limited in Japan during the 2011-2012 season. Although the evidence is not conclusive, co-circulating NIRVs may affect influenza VE estimates in test-negative case-control studies.
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118
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Dierig A, Heron LG, Lambert SB, Yin JK, Leask J, Chow MYK, Sloots TP, Nissen MD, Ridda I, Booy R. Epidemiology of respiratory viral infections in children enrolled in a study of influenza vaccine effectiveness. Influenza Other Respir Viruses 2014; 8:293-301. [PMID: 24483149 PMCID: PMC4181477 DOI: 10.1111/irv.12229] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2013] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Influenza-like illness (ILI) confers a high annual morbidity in young children. We report the epidemiology of ILIs in children who participated in an influenza vaccine effectiveness study during the 2010 Southern Hemisphere influenza season in Sydney, Australia. METHODS Children aged 0·5-3 years were prospectively recruited from child care centres (CCCs). We classified them as fully vaccinated, partially vaccinated and unvaccinated according to their receipt of unadjuvanted vaccines containing influenza A (H1N1)pdm09. For 13 weeks commencing 30 July 2010, parents reported when their children developed an ILI (fever ≥37·8°C/feverishness plus ≥1 respiratory symptom) and collected nose and/or throat swabs for multiplex respiratory virus polymerase chain reaction (PCR) testing. Health impacts were assessed by telephone interview at enrolment and two weeks after each ILI. RESULTS There were 124 ILIs reported in 105 of 381 enrolled children. Swabs were taken in 117 ILIs: 175 viruses were identified from 103 swabs. Adeno- and rhinoviruses were most frequently identified; 44% of swabs yielded multiple viruses. No virus was associated with more severe symptoms, although rhinovirus-related ILIs lasted longer. Nose swabs had a higher virus detection rate than throat swabs. Influenza-vaccinated children were 1·6 times (P = 0·001) more likely than unvaccinated children to have a non-influenza ILI. CONCLUSION Adeno- and rhinoviruses were the most common viruses causing ILI. Swabs taken by parents are an effective method for sample collection. Influenza-like illness was more common in children vaccinated against influenza in this observational study, but prior health-seeking behaviour may have contributed to this difference.
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Affiliation(s)
- Alexa Dierig
- National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, Westmead, NSW, Australia; University Children's Hospital both Basel, Basel, Switzerland
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119
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Rhinoviruses. VIRAL INFECTIONS OF HUMANS 2014. [PMCID: PMC7120790 DOI: 10.1007/978-1-4899-7448-8_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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120
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Camacho A, Cazelles B. Does homologous reinfection drive multiple-wave influenza outbreaks? Accounting for immunodynamics in epidemiological models. Epidemics 2013; 5:187-96. [PMID: 24267875 PMCID: PMC3863957 DOI: 10.1016/j.epidem.2013.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 09/06/2013] [Accepted: 09/23/2013] [Indexed: 11/24/2022] Open
Abstract
We model the primary immune responses to influenza infection in humans. We examine the interplay between immunological and epidemiological dynamics. The model explains cases of homologous reinfection reported during past pandemics. Three epidemic profiles can arise depending on the degree of population mixing. A substantial proportion of infected host would remain unprotected after the 2009 influenza pandemic.
Epidemiological models of influenza transmission usually assume that recovered individuals instantly develop a fully protective immunity against the infecting strain. However, recent studies have highlighted host heterogeneity in the development of this immune response, characterized by delay and even absence of protection, that could lead to homologous reinfection (HR). Here, we investigate how these immunological mechanisms at the individual level shape the epidemiological dynamics at the population level. In particular, because HR was observed during the successive waves of past pandemics, we assess its role in driving multiple-wave influenza outbreaks. We develop a novel mechanistic model accounting for host heterogeneity in the immune response. Immunological parameters are inferred by fitting our dynamical model to a two-wave influenza epidemic that occurred on the remote island of Tristan da Cunha (TdC) in 1971, and during which HR occurred in 92 of 284 islanders. We then explore the dynamics predicted by our model for various population settings. We find that our model can explain HR over both short (e.g. week) and long (e.g. month) time-scales, as reported during past pandemics. In particular, our results reveal that the HR wave on TdC was a natural consequence of the exceptional contact configuration and high susceptibility of this small and isolated community. By contrast, in larger, less mixed and partially protected populations, HR alone cannot generate multiple-wave outbreaks. However, in the latter case, we find that a significant proportion of infected hosts would remain unprotected at the end of the pandemic season and should therefore benefit from vaccination. Crucially, we show that failing to account for these unprotected individuals can lead to large underestimation of the magnitude of the first post-pandemic season. These results are relevant in the context of the 2009 A/H1N1 influenza post-pandemic era.
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Affiliation(s)
- A Camacho
- Eco-Evolution Mathématique, UMR 7625, CNRS-UPMC-ENS, 75230 Paris Cedex 05, France; Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom.
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121
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De Serres G, Skowronski DM, Wu XW, Ambrose CS. The test-negative design: validity, accuracy and precision of vaccine efficacy estimates compared to the gold standard of randomised placebo-controlled clinical trials. Euro Surveill 2013; 18. [DOI: 10.2807/1560-7917.es2013.18.37.20585] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Binary file ES_Abstracts_Final_ECDC.txt matches
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Affiliation(s)
- G De Serres
- Institut national de santé publique du Québec and Department of Social and Preventive Medicine, Laval University, Quebec, Canada
| | - D M Skowronski
- British Columbia Center for Disease Control, Vancouver Canada
| | - X W Wu
- MedImmune, Gaithersburg, MD, USA
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122
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Kwong JC, Campitelli MA, Gubbay JB, Peci A, Winter AL, Olsha R, Turner R, Rosella LC, Crowcroft NS. Vaccine effectiveness against laboratory-confirmed influenza hospitalizations among elderly adults during the 2010-2011 season. Clin Infect Dis 2013; 57:820-7. [PMID: 23788243 PMCID: PMC3749748 DOI: 10.1093/cid/cit404] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/06/2013] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Although annual influenza immunization is recommended for adults aged ≥65 years due to the substantial burden of illness, the evidence base for this recommendation is weak. Prior observational studies that examined influenza vaccine effectiveness against nonspecific serious outcomes suffered from selection bias and the lack of laboratory confirmation for influenza infection. The objective of this study was to determine the effectiveness of the 2010-2011 seasonal influenza vaccine against laboratory-confirmed influenza hospitalizations among community-dwelling elderly adults, a serious and highly specific outcome. METHODS We conducted a test-negative study of community-dwelling adults aged >65 years in Ontario, Canada. Respiratory specimens collected between 1 December 2010 and 30 April 2011 from patients admitted to acute care hospitals were tested for influenza using nucleic acid amplification techniques. Influenza vaccination was ascertained from physician billing claims through linkage to health administrative datasets. RESULTS Receipt of the 2010-2011 seasonal influenza vaccine was associated with a 42% (95% confidence interval, 29%-53%) reduction in laboratory-confirmed influenza hospitalizations. Vaccine effectiveness estimates were consistent across age groups, by sex, and regardless of outcome severity, timing of testing, and when considering individuals vaccinated <7 or <14 days prior to admission as unvaccinated. CONCLUSIONS Results of this study will better inform decision making regarding influenza vaccination of elderly adults. Similar analyses are needed annually due to antigenic drift and frequent changes in influenza vaccine composition. The linkage of routinely collected laboratory testing and health administrative data represents an efficient method for estimating influenza vaccine effectiveness that complements prospective studies.
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Affiliation(s)
- Jeffrey C Kwong
- Institute for Clinical Evaluative Sciences, 2075 Bayview Ave, Toronto, Ontario, Canada.
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123
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The case test-negative design for studies of the effectiveness of influenza vaccine. Vaccine 2013; 31:3104-9. [DOI: 10.1016/j.vaccine.2013.04.026] [Citation(s) in RCA: 213] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 01/09/2013] [Accepted: 04/10/2013] [Indexed: 11/23/2022]
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124
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Wong JY, Wu P, Nishiura H, Goldstein E, Lau EHY, Yang L, Chuang SK, Tsang T, Peiris JSM, Wu JT, Cowling BJ. Infection fatality risk of the pandemic A(H1N1)2009 virus in Hong Kong. Am J Epidemiol 2013; 177:834-40. [PMID: 23459950 DOI: 10.1093/aje/kws314] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
One measure of the severity of a pandemic influenza outbreak at the individual level is the risk of death among people infected by the new virus. However, there are complications in estimating both the numerator and denominator. Regarding the numerator, statistical estimates of the excess deaths associated with influenza virus infections tend to exceed the number of deaths associated with laboratory-confirmed infection. Regarding the denominator, few infections are laboratory confirmed, while differences in case definitions and approaches to case ascertainment can lead to wide variation in case fatality risk estimates. Serological surveillance can be used to estimate the cumulative incidence of infection as a denominator that is more comparable across studies. We estimated that the first wave of the influenza A(H1N1)pdm09 virus in 2009 was associated with approximately 232 (95% confidence interval: 136, 328) excess deaths of all ages in Hong Kong, mainly among the elderly. The point estimates of the risk of death on a per-infection basis increased substantially with age, from below 1 per 100,000 infections in children to 1,099 per 100,000 infections in those 60-69 years of age. Substantial variation in the age-specific infection fatality risk complicates comparison of the severity of different influenza strains.
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Affiliation(s)
- Jessica Y Wong
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
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125
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Lo YC, Chuang JH, Kuo HW, Huang WT, Hsu YF, Liu MT, Chen CH, Huang HH, Chang CH, Chou JH, Chang FY, Lin TY, Chiu WT. Surveillance and vaccine effectiveness of an influenza epidemic predominated by vaccine-mismatched influenza B/Yamagata-lineage viruses in Taiwan, 2011-12 season. PLoS One 2013; 8:e58222. [PMID: 23472161 PMCID: PMC3589334 DOI: 10.1371/journal.pone.0058222] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 02/01/2013] [Indexed: 01/12/2023] Open
Abstract
Introduction The 2011−12 trivalent influenza vaccine contains a strain of influenza B/Victoria-lineage viruses. Despite free provision of influenza vaccine among target populations, an epidemic predominated by influenza B/Yamagata-lineage viruses occurred during the 2011−12 season in Taiwan. We characterized this vaccine-mismatched epidemic and estimated influenza vaccine effectiveness (VE). Methods Influenza activity was monitored through sentinel viral surveillance, emergency department (ED) and outpatient influenza-like illness (ILI) syndromic surveillance, and case-based surveillance of influenza with complications and deaths. VE against laboratory-confirmed influenza was evaluated through a case-control study on ILI patients enrolled into sentinel viral surveillance. Logistic regression was used to estimate VE adjusted for confounding factors. Results During July 2011−June 2012, influenza B accounted for 2,382 (72.5%) of 3,285 influenza-positive respiratory specimens. Of 329 influenza B viral isolates with antigen characterization, 287 (87.2%) were B/Yamagata-lineage viruses. Proportions of ED and outpatient visits being ILI-related increased from November 2011 to January 2012. Of 1,704 confirmed cases of influenza with complications, including 154 (9.0%) deaths, influenza B accounted for 1,034 (60.7%) of the confirmed cases and 103 (66.9%) of the deaths. Reporting rates of confirmed influenza with complications and deaths were 73.5 and 6.6 per 1,000,000, respectively, highest among those aged ≥65 years, 50−64 years, 3−6 years, and 0−2 years. Adjusted VE was −31% (95% CI: −80, 4) against all influenza, 54% (95% CI: 3, 78) against influenza A, and −66% (95% CI: −132, −18) against influenza B. Conclusions This influenza epidemic in Taiwan was predominated by B/Yamagata-lineage viruses unprotected by the 2011−12 trivalent vaccine. The morbidity and mortality of this vaccine-mismatched epidemic warrants careful consideration of introducing a quadrivalent influenza vaccine that includes strains of both B lineages.
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Affiliation(s)
- Yi-Chun Lo
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | | | - Hung-Wei Kuo
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Wan-Ting Huang
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Yu-Fen Hsu
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Ming-Tsan Liu
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Chang-Hsun Chen
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Hui-Hsun Huang
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Chi-Hsi Chang
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Jih-Haw Chou
- Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Feng-Yee Chang
- Centers for Disease Control, Taipei, Taiwan, Republic of China
- Department of Internal Medicine and Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- * E-mail:
| | - Tzou-Yien Lin
- Department of Health, Taipei, Taiwan, Republic of China
| | - Wen-Ta Chiu
- Department of Health, Taipei, Taiwan, Republic of China
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Wu P, Goldstein E, Ho LM, Yang L, Nishiura H, Wu JT, Ip DKM, Chuang SK, Tsang T, Cowling BJ. Excess mortality associated with influenza A and B virus in Hong Kong, 1998-2009. J Infect Dis 2012; 206:1862-71. [PMID: 23045622 PMCID: PMC3502382 DOI: 10.1093/infdis/jis628] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Although deaths associated with laboratory-confirmed influenza virus infections are rare, the excess mortality burden of influenza estimated from statistical models may more reliably quantify the impact of influenza in a population. METHODS We applied age-specific multiple linear regression models to all-cause and cause-specific mortality rates in Hong Kong from 1998 through 2009. The differences between estimated mortality rates in the presence or absence of recorded influenza activity were used to estimate influenza-associated excess mortality. RESULTS The annual influenza-associated all-cause excess mortality rate was 11.1 (95% confidence interval [CI], 7.2-14.6) per 100,000 person-years. We estimated an average of 751 (95% CI, 488-990) excess deaths associated with influenza annually from 1998 through 2009, with 95% of the excess deaths occurring in persons aged ≥65 years. Most of the influenza-associated excess deaths were from respiratory (53%) and cardiovascular (18%) causes. Influenza A(H3N2) epidemics were associated with more excess deaths than influenza A(H1N1) or B during the study period. CONCLUSIONS Influenza was associated with a substantial number of excess deaths each year, mainly among the elderly, in Hong Kong in the past decade. The influenza-associated excess mortality rates were generally similar in Hong Kong and the United States.
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Affiliation(s)
- Peng Wu
- School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China
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Respiratory viruses in hospitalized children with influenza-like illness during the h1n1 2009 pandemic in Sweden [corrected]. PLoS One 2012; 7:e51491. [PMID: 23272110 PMCID: PMC3522717 DOI: 10.1371/journal.pone.0051491] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 11/05/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The swine-origin influenza A(H1N1)pdm09 pandemic of 2009 had a slower spread in Europe than expected. The human rhinovirus (HRV) has been suggested to have delayed the pandemic through viral interference. The importance of co-infections over time during the pandemic and in terms of severity of the disease needs to be assessed. OBJECTIVE The aim of this study was to investigate respiratory viruses and specifically the presence of co-infections with influenza A(H1N1)pdm09 (H1N1) in hospitalized children during the H1N1 pandemic. A secondary aim was to investigate if co-infections were associated with severity of disease. METHODS A retrospective study was performed on 502 children with influenza-like illness admitted to inpatient care at a pediatric hospital in Stockholm, Sweden during the 6 months spanning the H1N1 pandemic in 2009. Respiratory samples were analyzed for a panel of 16 viruses by real-time polymerase chain reaction. RESULTS One or more viruses were detected in 61.6% of the samples. Of these, 85.4% were single infections and 14.6% co-infections (2-4 viruses). The number of co-infections increased throughout the study period. H1N1 was found in 83 (16.5%) children and of these 12 (14.5%) were co-infections. HRV and H1N1 circulated to a large extent at the same time and 6.0% of the H1N1-positive children were also positive for HRV. There was no correlation between co-infections and severity of disease in children with H1N1. CONCLUSIONS Viral co-infections were relatively common in H1N1 infected hospitalized children and need to be considered when estimating morbidity attributed to H1N1. Population-based longitudinal studies with repeated sampling are needed to improve the understanding of the importance of co-infections and viral interference.
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128
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Virus Interference and Estimates of Influenza Vaccine Effectiveness from Test-Negative Studies. Epidemiology 2012; 23:930-1. [DOI: 10.1097/ede.0b013e31826b300e] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Cowling BJ, Ng S, Ma ESK, Fang VJ, So HC, Wai W, Cheng CKY, Wong JY, Chan KH, Ip DKM, Chiu SS, Peiris JSM, Leung GM. Protective Efficacy Against Pandemic Influenza of Seasonal Influenza Vaccination in Children in Hong Kong: A Randomized Controlled Trial. Clin Infect Dis 2012; 55:695-702. [DOI: 10.1093/cid/cis518] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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