Determinants for not keeping up to date with COVID-19 vaccination in the 2023 vaccination round among medical risk groups, the Netherlands

Vaccination is crucial to prevent severe COVID-19 in people in medical risk groups (MRG). Among MRG aged 18-59 years, vaccination coverage declined from 19 % in 2022 to 6 % in 2023. Among those aged ≥60 years, coverage declined from 61 % to 53 %. We explored determinants for not being vaccinated in 2023 among those vaccinated in 2022 ('vaccination dropout'), to inform strategies to improve coverage. We conducted a retrospective database study in the Dutch MRG population aged ≥18 years, assessing socio-demographic determinants for vaccination dropout by multivariable logistic regression. Among MRG vaccinated in 2022 (n = 1,593,265), dropout in 2023 was 33 %. For MRG <60 years, younger age was mostly strongly associated with dropout (aOR 18-24years 2.55; 95 % CI: 2.34-2.78. Reference: 55-59 years). Being in a household with children increased dropout, where non-married couples with children had an aOR (1.63, 1.57-1.69. Reference: married couples without children in the household). For MGR ≥60 years, younger age and lower income quartile was most strongly associated with dropout (aOR 60-64years 2.26; 2.21-2.31. Reference: 80+) and (aOR lowest quartile 1.80; 1.77-1.83. Reference: highest income quartile), respectively. In both age groups, lower medical risk, being born abroad, living in a non-urban area and lack of car-ownership were also associated with dropout. Being employed was associated with higher dropout rates. Living within 5 km of a vaccination location was associated with lower dropout. COVID-19 vaccine coverage among MRG in the Netherlands declined in 2023 compared to 2022. We identified several determinants for dropout, which are relevant for program optimization.