Seroprevalence of antibody to influenza A(H1N1)pdm09 attributed to vaccination or infection, before and after the second (2010) pandemic wave in Australia

摘要: Objectives Historical records of influenza pandemics demonstrate variability in incidence and severity between waves. The A(H1N1)pdm09 pandemic was the first which many countries implemented strain-specific vaccination to mitigate subsequent seasons. Serosurveys provide opportunity examine constraining influence antibody on population disease experience. Design Changes proportion adults seropositive A(H1N1)pdm09over 2009/10 (summer) interepidemic period 2010 (winter) season were measured determine whether there a temporal relationship with vaccine distribution activity, respectively. Setting Australia. Sample Plasma samples collected from healthy blood donors seven cities at end wave (November 2009), before (March/April 2010) after season. Main outcome measures Haemagglutination inhibition (HI) assays performed assess reactivity plasma against A(H1N1)pdm09, (HI titre ≥ 40) compared over time, by age group location. Results Between 2009 seasons, rose 22% 43%, an increase observed across all ages sites. Brisbane alone recorded significant rise seropositivity – baseline 35% 53%. elsewhere ≥40% pre-season, did not winter. Conclusions A vaccine-associated preceding correlated low levels activity winter 2010. These observations support role immunisation mitigating ‘second wave’ timing critical ensure sustained herd protection.