Real-time in-season monitoring of adult influenza vaccination coverage rates in Germany: results from a repeated cross-sectional online survey.

OBJECTIVE

Proof of concept to provide early estimates of influenza vaccination coverage rates (VCR) for adults in Germany during the 2024/25 season, explore variation across recommended risk groups, and identify reasons for/against vaccination.

METHODS

A web-based, repeated cross-sectional survey (Vakzimeter FLU) was conducted in five waves between October-2024 and February-2025 in Germany. Disproportionate sampling ensured adequate representation of adults aged ≥60 years; general population estimates were obtained after calibrated weighting to align the sample with national demographics. Respondents reported past and current influenza vaccination status, intention to get vaccinated, socio-demographics, chronic conditions, occupational and household risk factors, and reasons for/against getting vaccinated against influenza.

RESULTS

Among 5001 respondents (18-59 years, n = 1505; ≥60 years, n = 3496), VCR during survey wave 5 (February-2025) was 26% for adults aged 18-59 years overall, 32% for at-risk adults aged 18-59 years, and 51% for adults aged ≥60 years. Weighted estimate VCR of general population was 36%. All values were below the WHO target of 75% for risk groups. Although each survey wave included a separate set of participants, vaccination status patterns may hint towards older adults being more likely to follow through with intended vaccination, while younger adults may be more likely not to. Key reasons against vaccination included low perceived risk, belief that influenza is not severe, and concerns over vaccine effectiveness/safety. In the 18-59 age group, 46% indicated no vaccination in the current season and had not received an influenza vaccination for ≥5 consecutive seasons, reflecting persistent hesitancy.

CONCLUSION

This real-time monitoring approach provided timely, population-representative influenza VCR estimates during the influenza season, enabling in-season gap identification. Findings confirm persistent shortfalls in VCRs, particularly among younger adults, and reinforce the need for tailored, trust-building strategies to both convert stated intent into actual vaccination and boost initial willingness, especially in at-risk groups.