Article: The infection attack rate and severity of 2009 pandemic H1N1 influenza in Hong Kong

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TitleThe infection attack rate and severity of 2009 pandemic H1N1 influenza in Hong Kong
AuthorsWu, JT2
Ma, ESK2
Lee, CK1
Chu, DKW2
Ho, PL2
Shen, AL2
Ho, A2
Hung, IFN2
Riley, S2
Ho, LM2
Lin, CK1
Tsang, T3
Lo, SV1 5
Lau, YL2
Leung, GM2
Cowling, BJ2
Peiris, JSM2 4
Issue Date2010
PublisherOxford University Press. The Journal's web site is located at http://www.oxfordjournals.org/our_journals/cid/
CitationClinical Infectious Diseases, 2010, v. 51 n. 10, p. 1184-1191 [How to Cite?]
DOI: http://dx.doi.org/10.1086/656740
AbstractBackground. Serial cross-sectional data on antibody levels to the 2009 pandemic H1N1 influenza A virus from a population can be used to estimate the infection attack rates and immunity against future infection in the community. Methods. From April through December 2009, we obtained 12,217 serum specimens from blood donors (aged 16-59 years), 2520 specimens from hospital outpatients (aged 5-59 years), and 917 specimens from subjects involved in a community pediatric cohort study (aged 5-14 years). We estimated infection attack rates by comparing the proportions of specimens with antibody titers ≥1:40 by viral microneutralization before and after the first wave of the pandemic. Estimates were validated using paired serum samples from 324 individuals that spanned the first wave. Combining these estimates with epidemiologic surveillance data, we calculated the proportion of infections that led to hospitalization, admission to the intensive care unit (ICU), and death. Results. We found that 3.3% and 14% of persons aged 5-59 years had antibody titers ≥1:40 before and after the first wave, respectively. The overall attack rate was 10.7%, with age stratification as follows: 43.4% in persons aged 5-14 years, 15.8% in persons aged 15-19 years, 11.8% in persons aged 20-29 years, and 4%-4.6% in persons aged 30-59 years. Case-hospitalization rates were 0.47%-0.87% among persons aged 5-59 years. Case-ICU rates were 7.9 cases per 100,000 infections in persons aged 5-14 years and 75 cases per 100,000 infections in persons aged 50-59 years, respectively. Case-fatality rates were 0.4 cases per 100,000 infections in persons aged 5-14 years and 26.5 cases per 100,000 infections in persons aged 50-59 years, respectively. Conclusions. Almost half of all school-aged children in Hong Kong were infected during the first wave. Compared with school children aged 5-14 years, older adults aged 50-59 years had 9.5 and 66 times higher risks of ICU admission and death if infected, respectively. © 2010 by the Infectious Diseases Society of America. All rights reserved.
ISSN1058-4838
2011 Impact Factor: 9.154
2011 SCImago Journal Rankings: 0.821
DOIhttp://dx.doi.org/10.1086/656740
ISI Accession Number IDWOS:000283331800012
Funding AgencyGrant Number
Government of the Hong Kong SARPHE-20
PHE-2
Hong Kong University Grants CommitteeAoE/M-12/06
Harvard Center for Communicable Disease Dynamics from the US National Institutes of Health1 U54 GM088558
EMPERIE (EU)223498
National Institute of Allergy and Infectious Diseases
National Institutes of HealthHHSN266200700005C
N01-AI-70005
Funding Information:

Financial support. Research Fund for the Control of Infectious Disease, Food and Health Bureau, Government of the Hong Kong SAR (PHE-20 and PHE-2), the Area of Excellence Scheme of the Hong Kong University Grants Committee (AoE/M-12/06), the Harvard Center for Communicable Disease Dynamics from the US National Institutes of Health Models of Infectious Disease Agent Study program (1 U54 GM088558), EMPERIE (EU FP7 grant 223498), the National Institute of Allergy and Infectious Diseases, and the National Institutes of Health (HHSN266200700005C; ADB no. N01-AI-70005).

ReferencesReferences in Scopus
GrantsThe attack rate, transmission dynamics and viral evolution in a cohort of Hong Kong families during an epidemic of novel influenza virus (H1N1)
A detailed longitudinal study of infection attack rates among healthy adults in Hong Kong during the epidemic of the human swine influenza A/H1N1 virus in 2009
Control of Pandemic and Inter-pandemic Influenza
DC Field
Value
dc.contributor.authorWu, JT
dc.contributor.authorMa, ESK
dc.contributor.authorLee, CK
dc.contributor.authorChu, DKW
dc.contributor.authorHo, PL
dc.contributor.authorShen, AL
dc.contributor.authorHo, A
dc.contributor.authorHung, IFN
dc.contributor.authorRiley, S
dc.contributor.authorHo, LM
dc.contributor.authorLin, CK
dc.contributor.authorTsang, T
dc.contributor.authorLo, SV
dc.contributor.authorLau, YL
dc.contributor.authorLeung, GM
dc.contributor.authorCowling, BJ
dc.contributor.authorPeiris, JSM
dc.date.accessioned2010-12-23T08:37:41Z
dc.date.available2010-12-23T08:37:41Z
dc.date.issued2010
dc.description.abstractBackground. Serial cross-sectional data on antibody levels to the 2009 pandemic H1N1 influenza A virus from a population can be used to estimate the infection attack rates and immunity against future infection in the community. Methods. From April through December 2009, we obtained 12,217 serum specimens from blood donors (aged 16-59 years), 2520 specimens from hospital outpatients (aged 5-59 years), and 917 specimens from subjects involved in a community pediatric cohort study (aged 5-14 years). We estimated infection attack rates by comparing the proportions of specimens with antibody titers ≥1:40 by viral microneutralization before and after the first wave of the pandemic. Estimates were validated using paired serum samples from 324 individuals that spanned the first wave. Combining these estimates with epidemiologic surveillance data, we calculated the proportion of infections that led to hospitalization, admission to the intensive care unit (ICU), and death. Results. We found that 3.3% and 14% of persons aged 5-59 years had antibody titers ≥1:40 before and after the first wave, respectively. The overall attack rate was 10.7%, with age stratification as follows: 43.4% in persons aged 5-14 years, 15.8% in persons aged 15-19 years, 11.8% in persons aged 20-29 years, and 4%-4.6% in persons aged 30-59 years. Case-hospitalization rates were 0.47%-0.87% among persons aged 5-59 years. Case-ICU rates were 7.9 cases per 100,000 infections in persons aged 5-14 years and 75 cases per 100,000 infections in persons aged 50-59 years, respectively. Case-fatality rates were 0.4 cases per 100,000 infections in persons aged 5-14 years and 26.5 cases per 100,000 infections in persons aged 50-59 years, respectively. Conclusions. Almost half of all school-aged children in Hong Kong were infected during the first wave. Compared with school children aged 5-14 years, older adults aged 50-59 years had 9.5 and 66 times higher risks of ICU admission and death if infected, respectively. © 2010 by the Infectious Diseases Society of America. All rights reserved.
dc.description.grantThe attack rate, transmission dynamics and viral evolution in a cohort of Hong Kong families during an epidemic of novel influenza virus (H1N1)
dc.description.grantA detailed longitudinal study of infection attack rates among healthy adults in Hong Kong during the epidemic of the human swine influenza A/H1N1 virus in 2009
dc.description.grantControl of Pandemic and Inter-pandemic Influenza
dc.description.grantcode100761
dc.description.grantcode100759
dc.description.grantcode97655
dc.description.naturepublished_or_final_version
dc.identifier.citationClinical Infectious Diseases, 2010, v. 51 n. 10, p. 1184-1191 [How to Cite?]
DOI: http://dx.doi.org/10.1086/656740
dc.identifier.citeulike8122359
dc.identifier.doihttp://dx.doi.org/10.1086/656740
dc.identifier.epage1191
dc.identifier.hkuros183402
dc.identifier.hkuros203201
dc.identifier.isiWOS:000283331800012
Funding AgencyGrant Number
Government of the Hong Kong SARPHE-20
PHE-2
Hong Kong University Grants CommitteeAoE/M-12/06
Harvard Center for Communicable Disease Dynamics from the US National Institutes of Health1 U54 GM088558
EMPERIE (EU)223498
National Institute of Allergy and Infectious Diseases
National Institutes of HealthHHSN266200700005C
N01-AI-70005
Funding Information:

Financial support. Research Fund for the Control of Infectious Disease, Food and Health Bureau, Government of the Hong Kong SAR (PHE-20 and PHE-2), the Area of Excellence Scheme of the Hong Kong University Grants Committee (AoE/M-12/06), the Harvard Center for Communicable Disease Dynamics from the US National Institutes of Health Models of Infectious Disease Agent Study program (1 U54 GM088558), EMPERIE (EU FP7 grant 223498), the National Institute of Allergy and Infectious Diseases, and the National Institutes of Health (HHSN266200700005C; ADB no. N01-AI-70005).

dc.identifier.issn1058-4838
2011 Impact Factor: 9.154
2011 SCImago Journal Rankings: 0.821
dc.identifier.issue10
dc.identifier.pmid20964521
dc.identifier.scopuseid_2-s2.0-78349253122
dc.identifier.spage1184
dc.identifier.urihttp://hdl.handle.net/10722/129464
dc.identifier.volume51
dc.languageeng
dc.publisherOxford University Press. The Journal's web site is located at http://www.oxfordjournals.org/our_journals/cid/
dc.publisher.placeUnited States
dc.relation.ispartofClinical Infectious Diseases
dc.relation.referencesReferences in Scopus
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License
dc.subject.meshAdolescent
dc.subject.meshAdult
dc.subject.meshAntibodies, Viral - blood
dc.subject.meshChild
dc.subject.meshChild, Preschool
dc.subject.meshCross-Sectional Studies
dc.subject.meshDisease Outbreaks - statistics & numerical data
dc.subject.meshHong Kong - epidemiology
dc.subject.meshHumans
dc.subject.meshImmunoglobulin G - blood
dc.subject.meshInfluenza A Virus, H1N1 Subtype - immunology
dc.subject.meshInfluenza, Human - epidemiology - immunology - virology
dc.subject.meshMarkov Chains
dc.subject.meshMiddle Aged
dc.subject.meshMonte Carlo Method
dc.subject.meshNeutralization Tests
dc.subject.meshReproducibility of Results
dc.subject.meshSeroepidemiologic Studies
dc.titleThe infection attack rate and severity of 2009 pandemic H1N1 influenza in Hong Kong
dc.typeArticle
Author Affiliations
  1. Hong Kong Hospital Authority
  2. The University of Hong Kong Li Ka Shing Faculty of Medicine
  3. Centre for Health Protection
  4. HKU-Pasteur Research Centre
  5. Food and Health Bureau