Original scientific paper
Case-control study to measure influenza vaccine effectiveness during the 2008-2009, 2009-2010 and 2010-11 influenza seasons in Hungary
Beatrix Oroszi
; Office of the Chief Medical Officer, Budapest
Krisztina Judit Horváth
; Department of Infectious Diseases, National Center for Epidemiology, Budapest
Abstract
Resulting from the constant evolution of influenza viruses, influenza vaccine effectiveness can vary from year to year depending on the matching between the circulating strains and the ones that are included in the vaccine.Within a European programme to monitor seasonal and pandemic influenza vaccine effectiveness, the Hungarian team conducted case-control studies in 2008-9, 2009-10 and 2010-11. Sentinel GPs swabbed a systematic sample of patients consulting for influenza-like symptoms. Influenza confirmed cases were compared to influenza negative controls. Influenza vaccine effectiveness estimates were obtained using 1- odds ratio. We adjusted estimates for age-group, month of onset, chronic diseases, smoking, previous influenza vaccinations, previous hospitalisations and GP visits in the previous 12 months. In 2008-2009 50 GPs, in 2009-2010 87 GPs and in 2010-2011 98 GPs participated in the study. In 2009-2010 the adjusted pandemic influenza vaccine effectiveness was 79.1% (95% CI 12.8-95.0%) for 18+ age group, and 80.1% (95% CI: 7.7-95.7%) in the 18-59 age group. According to the preliminary results of the 2010-2011 study the adjusted seasonal influenza vaccine effectiveness was 85.6% (95% CI: 27.0-97.2%). During the pilot study in 2008-2009 the sample was too small to obtain vaccine effectiveness results.Case control study with the participation of GPs who are involved in the sentinel influenza surveillance system is feasible. Larger sample size is needed to achieve greater precision for subgroup analysis.
Keywords
influenza,influenza vaccine,vaccine effectiveness,communicable disease control,case control studies
Hrčak ID:
297171
URI
Publication date:
7.7.2011.
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