[Efficiency of seasonal influenza vaccine in persons older than 65 in Romania. Pilot case-control study I-MOVE,...

Cantacuzino Institute conducted between September 2008 and June 2009, a pilot case-control study to monitor the influenza vaccine effectiveness on people over 65 years of age from Romania. This study is part of the I-MOVE project "Monitoring the vaccine effectiveness during seasonal and pandemic influenza in EU/EEA member states, 2008-2009", coordinated by EpiConcept, France and financed by European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden. Forty seven family doctors and epidemiologists from Bucharest and seven influenza sentinel districts were selected to participate in this project, based on epidemiological and geographical criteria. Family doctors swabbed all people over 65-years-old consulting for influenza like illness (ILI). Influenza confirmed cases (classified as cases) were compared to influenza negative controls. Influenza vaccine effectiveness (IVE) was obtained using the formula: 1 - odds ratio, with 95% confidence interval (CI). One hundred and three ILI patients were enrolled in the study. Ninety nine from them (96.1%) were swabbed in the first 7 days after the onset, met the inclusion criteria and case definition and were included in analysis. Thirty (30.3%) were ILI flu positive and were classified as cases, sixty nine (69.7%) were ILI flu negative and classified as controls. Influenza vaccine effectiveness adjusted for the predefined set of confounders (age, sex, chronic diseases, smoking, previous influenza vaccination, functional status) was 86.8% (95% CI, 38.0, 97.2); influenza vaccine coverage in people older than 65 years was 49.4%. The result of the study showed a high influenza vaccine effectiveness in the elderly. In order to achieve a greater precision, the national and also the European samples should be extended for the next season.