a1 Beijing Center for Disease Prevention and Control (CDC), Capital Medical University School of Public Health and Family Medicine, Beijing, China
a2 School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia
In order to determine the prevalence of antibody against 2009 H1N1 influenza in Beijing, we conducted a serological survey in 710 subjects, 1 month after the epidemic peak. We found that 13·8% of our cohort was seropositive. Subjects aged ⩾60 years recorded the lowest seroprevalence (4·5%). The age-weighted seroprevalence of 14·0% was far lower than the supposed infection rate at the epidemic peak, derived from the basic reproduction number for 2009 H1N1 virus. For subjects who had received the pandemic vaccine seroprevalence was 51·4%. In subjects aged ⩾60 years the seasonal influenza vaccination was not significantly associated with being seropositive. Our study suggests that many factors, and not just the immunological level against 2009 H1N1 influenza in the community, affected the spread of the virus within the population of Beijing.
(Accepted August 25 2010)
(Online publication September 21 2010)
c1 Author for correspondence: Dr X. H. Pang, Beijing Center for Disease Prevention and Control (CDC), Capital Medical University School of Public Health and Family Medicine, Beijing 100013, China. (Email: firstname.lastname@example.org)