The epidemiology of the first wave of H1N1 Influenza pandemic in Australia: a population-based study

Pasco, Julie A., Nicholson, Geoff C., Brennan, Sharon L., Bennett, Kathy E., Dobbins, Amelia G. and Athan, Eugene (2012) The epidemiology of the first wave of H1N1 Influenza pandemic in Australia: a population-based study. The Open Public Health Journal, 5 80-85. doi:10.2174/1874944501205010080

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Author Pasco, Julie A.
Nicholson, Geoff C.
Brennan, Sharon L.
Bennett, Kathy E.
Dobbins, Amelia G.
Athan, Eugene
Title The epidemiology of the first wave of H1N1 Influenza pandemic in Australia: a population-based study
Journal name The Open Public Health Journal   Check publisher's open access policy
ISSN 1874-9445
Publication date 2012
Sub-type Article (original research)
DOI 10.2174/1874944501205010080
Open Access Status DOI
Volume 5
Start page 80
End page 85
Total pages 6
Place of publication Bussum, Netherlands
Publisher Bentham Open
Collection year 2013
Language eng
Formatted abstract
Objectives: Following the recent H1N1 influenza pandemic we were able to describe seropositivity in a repre-sentative sample of adults prior to the availability of a specific vaccine.
Methods: This cross-sectional serological study is set in the Barwon Statistical Division, Australia. Blood samples were collected from September 2009 through to May 2010, from 1184 individuals (569 men, 615 women; median age 61.7 years), randomly selected from electoral rolls. Serum was analysed for specific H1N1 immunity using a haemagglutina-tion inhibition test. A self-report provided information about symptoms, demographics and healthcare. Associations be-tween H1N1 infection, gender, households and occupation were determined using logistic regression, adjusting for age.
Results: Of 1184 individuals, 129 (58 men, 71 women) were seropositive. Gender-adjusted age-specific prevalence was: 8.3% 20-29 years, 13.5% 30-39, 10.4% 40-49, 6.5% 50-59, 9.7% 60-69, 10.3% 70-79, 18.8% 80+. Standardised preva-lence was 10.3% (95%CI 9.6-11.0). No associations were detected between seropositivity and gender (OR=0.82, 95%CI 0.57-1.19) or being a healthcare worker (OR=1.43, 95%CI 0.62-3.29). Smokers (OR=1.86, 95%CI 1.09-3.15) and those socioeconomically disadvantaged (OR=2.52, 95%CI 1.24-5.13) were at increased risk. Among 129 seropositive individu-als, 31 reported symptoms that were either mild (n = 13) or moderate (time off work, doctor visit, n = 18). For age <60, 39.6% of seropositive individuals reported symptoms, whereas the proportion was 13.2% for age 60+.
Conclusions: Following the pandemic, the proportion of seropositive adults was low, but significant subclinical infection was found. Social disadvantage increased the likelihood of infection. The low symptom rate for older ages may relate to pre-existing immunity.
Keyword Epidemiology
Influenza A virus
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Medicine Publications
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Created: Wed, 17 Apr 2013, 14:32:00 EST by Erin Bowly on behalf of Rural Clinical School