Influenza vaccination among high-risk subgroups in eleven European countries: findings from the Survey of Health, Ageing and Retirement in Europe (SHARE)

Abstract

Background: The risk of influenza-related complications is elevated in older adults and in persons with one or more chronic diseases. Vaccination of such individuals is therefore recommended in Europe as a preventive measure. We aimed to compare between European countries 1) to what extent high-risk subgroups receive influenza vaccination and 2) how likely they are to receive vaccination compared to the non-risk group. Methods: We used data from the Survey of Health, Ageing and Retirement in Europe collected in 2004/05. Adults aged 50+ years from eleven countries (Austria, Belgium, Denmark, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden, Switzerland) were asked whether they had received flu vaccination in the previous year. Using self-reported data from 16,182 individuals, we defined several high-risk subgroups (age 65+, presence of chronic lung disease [CLD], cardiovascular disease [CVD], diabetes/high glucose level). We calculated weighted and design-adjusted estimates of vaccination prevalence with 95% confidence intervals (CI) for each country. Country-specific multivariable logistic regression was used to explore associations between membership in a high-risk subgroup and vaccination uptake. Results: The prevalence of influenza vaccination in high-risk subgroups was generally highest in the Netherlands (e.g., 76.7% [95% CI: 73.6%, 79.8%] for those aged 65+ years and 74.6% [95% CI: 68.3%, 80.9%] for CLD) and was consistently lowest in Greece (26.3% [95% CI: 23.2%, 29.3%] and 18.5% [95% CI: 11.3%, 25.6%], respectively). Comparison of multivariable models suggested substantial cross-national variation in targeted influenza prevention. The adjusted odds of self-reported vaccination in those aged 65+ (versus <65), for example, ranged from 2 (Austria and Germany) to more than 10 (Denmark and the Netherlands). Conclusions: Influenza vaccination coverage among high-risk subgroups varies considerably between European countries. Most countries did not achieve recommended coverage rates; some fell well below recommendations, raising questions about the effectiveness of national efforts in reaching high-risk individuals.