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Article: Epidemiological characteristics of 2009 (H1N1) pandemic influenza based on paired sera from a longitudinal community cohort study
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TitleEpidemiological characteristics of 2009 (H1N1) pandemic influenza based on paired sera from a longitudinal community cohort study
 
AuthorsRiley, S4 3
Kwok, KO3
Wu, KM3
Ning, DY3
Cowling, BJ3
Wu, JT3
Ho, LM3
Tsang, T6
Lo, SV2
Chu, DKW1
Ma, ESK2
Peiris, JSM1 5
 
Issue Date2011
 
PublisherPublic Library of Science. The Journal's web site is located at http://medicine.plosjournals.org/perlserv/?request=index-html&issn=1549-1676
 
CitationPlos Medicine, 2011, v. 8 n. 6 [How to Cite?]
DOI: http://dx.doi.org/10.1371/journal.pmed.1000442
 
AbstractBackground: While patterns of incidence of clinical influenza have been well described, much uncertainty remains over patterns of incidence of infection. The 2009 pandemic provided both the motivation and opportunity to investigate patterns of mild and asymptomatic infection using serological techniques. However, to date, only broad epidemiological patterns have been defined, based on largely cross-sectional study designs with convenience sampling frameworks. Methods and Findings: We conducted a paired serological survey of a cohort of households in Hong Kong, recruited using random digit dialing, and gathered data on severe confirmed cases from the public hospital system (>90% inpatient days). Paired sera were obtained from 770 individuals, aged 3 to 103, along with detailed individual-level and household-level risk factors for infection. Also, we extrapolated beyond the period of our study using time series of severe cases and we simulated alternate study designs using epidemiological parameters obtained from our data. Rates of infection during the period of our study decreased substantially with age: for 3-19 years, the attack rate was 39% (31%-49%); 20-39 years, 8.9% (5.3%-14.7%); 40-59 years, 5.3% (3.5%-8.0%); and 60 years or older, 0.77% (0.18%-4.2%). We estimated parameters for a parsimonious model of infection in which a linear age term and the presence of a child in the household were used to predict the log odds of infection. Patterns of symptom reporting suggested that children experienced symptoms more often than adults. The overall rate of confirmed pandemic (H1N1) 2009 influenza (H1N1pdm) deaths was 7.6 (6.2-9.5) per 100,000 infections. However, there was substantial and progressive increase in deaths per 100,000 infections with increasing age from 0.66 (0.65-0.86) for 3-19 years up to 220 (50-4,000) for 60 years and older. Extrapolating beyond the period of our study using rates of severe disease, we estimated that 56% (43%-69%) of 3-19 year olds and 16% (13%-18%) of people overall were infected by the pandemic strain up to the end of January 2010. Using simulation, we found that, during 2009, larger cohorts with shorter follow-up times could have rapidly provided similar data to those presented here. Conclusions: Should H1N1pdm evolve to be more infectious in older adults, average rates of severe disease per infection could be higher in future waves: measuring such changes in severity requires studies similar to that described here. The benefit of effective vaccination against H1N1pdm infection is likely to be substantial for older individuals. Revised pandemic influenza preparedness plans should include prospective serological cohort studies. Many individuals, of all ages, remained susceptible to H1N1pdm after the main 2009 wave in Hong Kong. © 2011 Riley et al.
 
ISSN1549-1277
2012 SCImago Journal Rankings: 4.105
 
DOIhttp://dx.doi.org/10.1371/journal.pmed.1000442
 
PubMed Central IDPMC3119689
 
ISI Accession Number IDWOS:000292136800003
Funding AgencyGrant Number
Research Fund for the Control of Infectious Disease, Food and Health Bureau, Government of the Hong Kong SARPHE-21
Fogarty International Centre with the Science & Technology Directorate, Department of Homeland Security
Fogarty International CentreR01 TW008246-01
Hong Kong University Grants CommitteeAoE/M-12/06
US National Institutes of Health
Wellcome Trust093488/Z/10/Z
MedImmune Inc.
GlaxoSmithKline
Baxter
Cruxell
Combinatorix
DIVA Solutions
Funding Information:

This project was supported by: the Research Fund for the Control of Infectious Disease, Food and Health Bureau, Government of the Hong Kong SAR (PHE-21); the RAPIDD program from Fogarty International Centre with the Science & Technology Directorate, Department of Homeland Security; R01 TW008246-01 from Fogarty International Centre; the Area of Excellence Scheme of the Hong Kong University Grants Committee (AoE/M-12/06); US National Institutes of Health Models of Infectious Disease Agent Study program; and a Wellcome Trust University Award 093488/Z/10/Z. The funding bodies had no role in study design, data collection and analysis, preparation of the manuscript, or the decision to publish.

 
ReferencesReferences in Scopus
 
GrantsControl of Pandemic and Inter-pandemic Influenza
A longitudinal community study of influenza virus infections in Hong Kong
 
DC FieldValue
dc.contributor.authorRiley, S
 
dc.contributor.authorKwok, KO
 
dc.contributor.authorWu, KM
 
dc.contributor.authorNing, DY
 
dc.contributor.authorCowling, BJ
 
dc.contributor.authorWu, JT
 
dc.contributor.authorHo, LM
 
dc.contributor.authorTsang, T
 
dc.contributor.authorLo, SV
 
dc.contributor.authorChu, DKW
 
dc.contributor.authorMa, ESK
 
dc.contributor.authorPeiris, JSM
 
dc.date.accessioned2011-07-27T01:38:55Z
 
dc.date.available2011-07-27T01:38:55Z
 
dc.date.issued2011
 
dc.description.abstractBackground: While patterns of incidence of clinical influenza have been well described, much uncertainty remains over patterns of incidence of infection. The 2009 pandemic provided both the motivation and opportunity to investigate patterns of mild and asymptomatic infection using serological techniques. However, to date, only broad epidemiological patterns have been defined, based on largely cross-sectional study designs with convenience sampling frameworks. Methods and Findings: We conducted a paired serological survey of a cohort of households in Hong Kong, recruited using random digit dialing, and gathered data on severe confirmed cases from the public hospital system (>90% inpatient days). Paired sera were obtained from 770 individuals, aged 3 to 103, along with detailed individual-level and household-level risk factors for infection. Also, we extrapolated beyond the period of our study using time series of severe cases and we simulated alternate study designs using epidemiological parameters obtained from our data. Rates of infection during the period of our study decreased substantially with age: for 3-19 years, the attack rate was 39% (31%-49%); 20-39 years, 8.9% (5.3%-14.7%); 40-59 years, 5.3% (3.5%-8.0%); and 60 years or older, 0.77% (0.18%-4.2%). We estimated parameters for a parsimonious model of infection in which a linear age term and the presence of a child in the household were used to predict the log odds of infection. Patterns of symptom reporting suggested that children experienced symptoms more often than adults. The overall rate of confirmed pandemic (H1N1) 2009 influenza (H1N1pdm) deaths was 7.6 (6.2-9.5) per 100,000 infections. However, there was substantial and progressive increase in deaths per 100,000 infections with increasing age from 0.66 (0.65-0.86) for 3-19 years up to 220 (50-4,000) for 60 years and older. Extrapolating beyond the period of our study using rates of severe disease, we estimated that 56% (43%-69%) of 3-19 year olds and 16% (13%-18%) of people overall were infected by the pandemic strain up to the end of January 2010. Using simulation, we found that, during 2009, larger cohorts with shorter follow-up times could have rapidly provided similar data to those presented here. Conclusions: Should H1N1pdm evolve to be more infectious in older adults, average rates of severe disease per infection could be higher in future waves: measuring such changes in severity requires studies similar to that described here. The benefit of effective vaccination against H1N1pdm infection is likely to be substantial for older individuals. Revised pandemic influenza preparedness plans should include prospective serological cohort studies. Many individuals, of all ages, remained susceptible to H1N1pdm after the main 2009 wave in Hong Kong. © 2011 Riley et al.
 
dc.description.naturepublished_or_final_version
 
dc.identifier.citationPlos Medicine, 2011, v. 8 n. 6 [How to Cite?]
DOI: http://dx.doi.org/10.1371/journal.pmed.1000442
 
dc.identifier.doihttp://dx.doi.org/10.1371/journal.pmed.1000442
 
dc.identifier.eissn1549-1676
 
dc.identifier.hkuros186375
 
dc.identifier.isiWOS:000292136800003
Funding AgencyGrant Number
Research Fund for the Control of Infectious Disease, Food and Health Bureau, Government of the Hong Kong SARPHE-21
Fogarty International Centre with the Science & Technology Directorate, Department of Homeland Security
Fogarty International CentreR01 TW008246-01
Hong Kong University Grants CommitteeAoE/M-12/06
US National Institutes of Health
Wellcome Trust093488/Z/10/Z
MedImmune Inc.
GlaxoSmithKline
Baxter
Cruxell
Combinatorix
DIVA Solutions
Funding Information:

This project was supported by: the Research Fund for the Control of Infectious Disease, Food and Health Bureau, Government of the Hong Kong SAR (PHE-21); the RAPIDD program from Fogarty International Centre with the Science & Technology Directorate, Department of Homeland Security; R01 TW008246-01 from Fogarty International Centre; the Area of Excellence Scheme of the Hong Kong University Grants Committee (AoE/M-12/06); US National Institutes of Health Models of Infectious Disease Agent Study program; and a Wellcome Trust University Award 093488/Z/10/Z. The funding bodies had no role in study design, data collection and analysis, preparation of the manuscript, or the decision to publish.

 
dc.identifier.issn1549-1277
2012 SCImago Journal Rankings: 4.105
 
dc.identifier.issue6
 
dc.identifier.openurl
 
dc.identifier.pmcidPMC3119689
 
dc.identifier.pmid21713000
 
dc.identifier.scopuseid_2-s2.0-79959809606
 
dc.identifier.urihttp://hdl.handle.net/10722/135660
 
dc.identifier.volume8
 
dc.languageeng
 
dc.publisherPublic Library of Science. The Journal's web site is located at http://medicine.plosjournals.org/perlserv/?request=index-html&issn=1549-1676
 
dc.publisher.placeUnited States
 
dc.relation.ispartofPLoS Medicine
 
dc.relation.projectControl of Pandemic and Inter-pandemic Influenza
 
dc.relation.projectA longitudinal community study of influenza virus infections in Hong Kong
 
dc.relation.referencesReferences in Scopus
 
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License
 
dc.subject.meshHong Kong - epidemiology
 
dc.subject.meshInfluenza A Virus, H1N1 Subtype - physiology
 
dc.subject.meshInfluenza, Human - blood - epidemiology - virology
 
dc.subject.meshPandemics - statistics and numerical data
 
dc.subject.meshResidence Characteristics - statistics and numerical data
 
dc.titleEpidemiological characteristics of 2009 (H1N1) pandemic influenza based on paired sera from a longitudinal community cohort study
 
dc.typeArticle
 
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<contributor.author>Wu, KM</contributor.author>
<contributor.author>Ning, DY</contributor.author>
<contributor.author>Cowling, BJ</contributor.author>
<contributor.author>Wu, JT</contributor.author>
<contributor.author>Ho, LM</contributor.author>
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Author Affiliations
  1. The University of Hong Kong Li Ka Shing Faculty of Medicine
  2. Hong Kong Hospital Authority
  3. The University of Hong Kong
  4. Imperial College London
  5. HKU-Pasteur Research Centre
  6. Centre for Health Protection