Risk factors and immunity in a nationally representative population following the 2009 influenza A(H1N1) pandemic

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dc.contributor.author Bandaranayake, D en
dc.contributor.author Huang, S en
dc.contributor.author Bissielo, A en
dc.contributor.author Wood, T en
dc.contributor.author Mackereth, G en
dc.contributor.author Baker, MG en
dc.contributor.author Beasley, R en
dc.contributor.author Reid, S en
dc.contributor.author Roberts, S en
dc.contributor.author Hope, V en
dc.contributor.author on behalf of 2009 H1N1 serosurvey investigation team en
dc.date.accessioned 2017-07-11T21:07:16Z en
dc.date.issued 2010-10 en
dc.identifier.citation PLoS ONE 5(10):e13211 Oct 2010 en
dc.identifier.uri http://hdl.handle.net/2292/34164 en
dc.description.abstract BACKGROUND: Understanding immunity, incidence and risk factors of the 2009 influenza A(H1N1) pandemic (2009 H1N1) through a national seroprevalence study is necessary for informing public health interventions and disease modelling. METHODS AND FINDINGS: We collected 1687 serum samples and individual risk factor data between November-2009 to March-2010, three months after the end of the 2009 H1N1 wave in New Zealand. Participants were randomly sampled from selected general practices countrywide and hospitals in the Auckland region. Baseline immunity was measured from 521 sera collected during 2004 to April-2009. Haemagglutination inhibition (HI) antibody titres of ≥1:40 against 2009 H1N1 were considered seroprotective as well as seropositive. The overall community seroprevalence was 26.7% (CI:22.6-29.4). The seroprevalence varied across age and ethnicity. Children aged 5-19 years had the highest seroprevalence (46.7%;CI:38.3-55.0), a significant increase from the baseline (14%;CI:7.2-20.8). Older adults aged ≥60 had no significant difference in seroprevalence between the serosurvey (24.8%;CI:18.7-30.9) and baseline (22.6%;CI:15.3-30.0). Pacific peoples had the highest seroprevalence (49.5%;CI:35.1-64.0). There was no significant difference in seroprevalence between both primary (29.6%;CI:22.6-36.5) and secondary healthcare workers (25.3%;CI:20.8-29.8) and community participants. No significant regional variation was observed. Multivariate analysis indicated age as the most important risk factor followed by ethnicity. Previous seasonal influenza vaccination was associated with higher HI titres. Approximately 45.2% of seropositive individuals reported no symptoms. CONCLUSIONS: Based on age and ethnicity standardisation to the New Zealand Population, about 29.5% of New Zealanders had antibody titers at a level consistent with immunity to 2009 H1N1. Around 18.3% of New Zealanders were infected with the virus during the first wave including about one child in every three. Older people were protected due to pre-existing immunity. Age was the most important factor associated with infection followed by ethnicity. Healthcare workers did not appear to have an increased risk of infection compared with the general population. en
dc.publisher Public Library of Science (PLoS) en
dc.relation.ispartofseries PLoS ONE en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from http://www.sherpa.ac.uk/romeo/issn/1932-6203/ en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.rights.uri https://creativecommons.org/licenses/by/4.0/ en
dc.title Risk factors and immunity in a nationally representative population following the 2009 influenza A(H1N1) pandemic en
dc.type Journal Article en
dc.identifier.doi 10.1371/journal.pone.0013211 en
pubs.issue 10 en
pubs.volume 5 en
dc.description.version VoR - Version of Record en
dc.rights.holder Copyright: The Authors en
dc.rights.accessrights http://purl.org/eprint/accessRights/OpenAccess en
pubs.subtype Article en
pubs.elements-id 467167 en
pubs.org-id Medical and Health Sciences en
pubs.org-id School of Medicine en
pubs.org-id Paediatrics Child & Youth Hlth en
dc.identifier.eissn 1932-6203 en
pubs.number e13211 en
pubs.record-created-at-source-date 2014-12-04 en

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