title: H1N1v at a seroepidemiological glance: is the nightmare over?
abstract: When the second wave of pandemic influenza A H1N1v 2009 (H1N1v) emerged in the winter of 2010/2011, public health authorities were afraid of dangerous implications and severe clinical courses again. As further H1N1v waves might appear, achievement of sufficient herd immunity is a matter of urgency. The objective of this study was to determine the seroprevalence of antibodies against H1N1v by hemagglutination-inhibition test (HI) after the second wave. We compared our recent findings with our data obtained after the first pandemic in 2009/2010. Between March and May 2011 we collected serum samples from 600 persons aged 1 to 84 years admitted to University Hospital Frankfurt/Main and analysed the titres of anti-H1N1v by HI. The overall seroprevalence of anti-H1N1v has risen from 36.9% (95% confidence interval (95%CI), 33-41) in unvaccinated persons after the first wave to 57.3% (95%CI, 53.1-61.2) in vaccinated and unvaccinated. The highest rate of seropositivity was detected in the age group of 10-19 years (66%; 95%CI, 55.8-75.2), whereas the lowest was found in the age group 40-59 years (51%; 95%CI, 40.8-61.1). Although seroprevalence has significantly increased, sufficient herd immunity is still not achieved. Therefore, general vaccination programs have to be propagated continuously by public health authorities.
authors: Institute for Medical Virology, University Hospital Frankfurt am Main, Paul-Ehrlich-Straße 40, 60596, Frankfurt am Main, Germany. claudia.reinheimer@kgu.de
authors: C
authors: C
authors: Reinheimer
authors: H W
authors: HW
authors: Doerr
authors: I
authors: I
authors: Friedrichs
authors: M
authors: M
authors: Stürmer
authors: R
authors: R
authors: Allwinn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005858:Germany / Q000453:epidemiology; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D032521:Immunity, Herd; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification* / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology / Q000821:virology*; D008297:Male; D008875:Middle Aged; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral