The impact of free influenza vaccination schemes on vaccine uptake among older adults in Europe, 2019-2020.

We investigated the causal effect of free influenza vaccination schemes on vaccination uptake among adults aged 50 years and older across 25 European countries. All countries conducted annual information campaigns targeting older adults, but differed in whether vaccination was provided free of charge at the point of delivery and in the age at which eligibility began. Using cross-sectional data from the 2019/2020 Survey of Health, Ageing and Retirement in Europe (SHARE), we exploited this institutional variation through a difference-in-discontinuities design that compared age-based discontinuities in vaccination uptake across countries with and without free vaccination schemes, rather than relying on similarity in individual characteristics. We found that offering vaccination free of charge increased influenza vaccine uptake by around 6 percentage points at the eligibility threshold. By contrast, no discontinuity was observed in countries relying exclusively on information campaigns. These findings indicate that free access substantially increased vaccination coverage beyond the effect of information provision alone. We further found no evidence that the effect differed systematically by household income, suggesting that free vaccination schemes operated not only through the removal of direct financial barriers but also through broader reductions in non-financial frictions. Overall, our findings highlight free access as an effective policy instrument for increasing influenza vaccination uptake among older adults.