The associations between childhood vaccine history and COVID-19 vaccine uptake among older adults in 28 high-income countries.

Background: Increasing vaccination uptake is critical for population health. However, little is known about the how childhood vaccination affects vaccination intake in adulthood. This study aims to examine the long-term associations between childhood vaccination history and COVID-19 vaccine uptake among older adults. Method: The study utilized data from the Survey of Health, Aging and Retirement in Europe, which included information on demographic variables, childhood vaccination, and COVID-19 vaccine uptake. Daily COVID-19 stringency data from Our World in Data was also incorporated into the study. The study cohort consisted of 48,963 participants from 27 European countries and Israel, of whom 81% (39,653) were vaccinated against COVID-19. A lasso regression machine learning approach was utilized to identify key confounders from a pool of 19 potential confounders. Logistic regression was then used to analyze the association between childhood vaccination and COVID -19 vaccine uptake in later life. Result: Childhood vaccination was found to be associated with COVID-19 vaccine uptake among middle-aged and older adults (OR = 1.66, 95% CI = [1.42, 1.94], p < 0.001) after adjusting for 16 demographics, mitigation behavior and COVID-19-related variables. Older age significantly enhanced this association. Conclusions: This study is the first to demonstrate a significant association between childhood vaccine history and adult vaccine behavior. This highlights the importance of childhood vaccination status in promoting COVID-19 vaccination among older adults. These findings support policies that emphasize the long-term value of childhood vaccination.