Factors associated with COVID-19 autumn 2022 booster uptake in the Netherlands among older adults aged ≥ 60 years and younger adults with chronic conditions.

ABSTRACT

BACKGROUND: A booster with bivalent COVID-19 vaccine was offered in the Netherlands in autumn, 2022. We aimed to investigate vaccine uptake during the autumn 2022 booster round among the population subgroups at risk for severe COVID-19 that were specifically targeted by this campaign the medical risk group aged 18-59 years and individuals ≥ 60 years. We calculated booster uptake in both populations and analyzed determinants of booster uptake among those who had received at least one prior COVID-19 vaccination. METHODS: Having had an autumn 2022 booster dose was defined as having received a COVID-19 vaccination between 19 September 2022 and 7 March 2023. The study population included individuals who received at least one previous COVID-19 vaccination. National registries of sociodemographic determinants and COVID-19 vaccination were linked by a unique person identifier. Voting proportions for political parties were included at neighborhood level. Determinants of COVID-19 vaccine autumn booster uptake were ranked by importance by random forest analyses. RESULTS: Booster uptake was 68 % among those aged ≥ 60 and 30 % among those aged 18-59 years with a medical risk factor for severe disease. For both target groups the most important determinant for booster uptake was age (15 % in 18-29 years to 72 % in 80 + years). Voting proportions for progressive liberal political parties ranked second in the random forest analysis in both groups, with an increasing proportion of votes associated with higher uptake. In the 60 + group, household type ranked third, with highest vaccine uptake among married couples without children (72 %) and the lowest uptake among unmarried couples with children (47 %). In the medical risk group, migration status ranked third. Migrants with two parents born abroad had the lowest uptake (18 %), whereas migrants with both parents born in the Netherlands had the highest uptake (35 %). CONCLUSION: The target group of people aged ≥ 60 years was much better reached than the target group of people with a medical risk aged 18-59 years. Uptake varied considerably among subgroups in both target groups. The findings of this study can be used in future vaccination strategies as well as for further research to better understand the drivers and barriers of vaccine uptake among the subgroups with notably low uptake.