Epidemiological Characteristics of 2009 (H1N1) Pandemic Influenza Based on Paired Sera from a Longitudinal Community Cohort Study
2011

Epidemiological Characteristics of 2009 (H1N1) Pandemic Influenza in Hong Kong

Sample size: 770 publication 10 minutes Evidence: moderate

Author Information

Author(s): Steven Riley, Kwok Kin O., Wu Kendra M., Ning Danny Y., Cowling Benjamin J., Wu Joseph T., Ho Lai-Ming, Tsang Thomas, Lo Su-Vui, Chu Daniel K. W., Ma Edward S. K., Peiris J. S. Malik

Primary Institution: MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London

Hypothesis

What are the patterns of infection incidence during the 2009 H1N1 pandemic in Hong Kong?

Conclusion

The study found that more children than adults were infected with H1N1, but children were less likely to progress to severe disease than adults.

Supporting Evidence

  • Rates of H1N1 infection decreased substantially with age.
  • The overall rate of confirmed H1N1 deaths was 7.6 per 100,000 infections.
  • 56% of 3–19 year olds were estimated to be infected by the pandemic strain.
  • Older adults had a much higher risk of severe disease despite lower infection rates.

Takeaway

This study looked at how many people got sick from the H1N1 flu in Hong Kong and found that kids got sick more often than adults, but adults were more likely to get really sick.

Methodology

A paired serological survey was conducted on a cohort of households in Hong Kong, with data collected on severe confirmed cases from the public hospital system.

Potential Biases

Potential sampling bias as individuals more likely to participate may have different probabilities of infection.

Limitations

The study did not measure incidence in children aged 2 and lower and may have sampling bias due to low response rates.

Participant Demographics

Participants ranged in age from 3 to 103 years, with a skew towards older adults and a higher participation rate among women.

Statistical Information

P-Value

0.05

Confidence Interval

31%–49%

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.1371/journal.pmed.1000442

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