COVID-19 vaccinations and mental health among U.S. adults: Individual and spillover effects

RATIONALE: The COVID-19 pandemic led to dramatic increases not only in physical illness, but also in mental health symptoms and disorders among U.S. adults. Although the introduction of COVID-19 vaccines dramatically lowered rates of physical illness and death, little is known about the effects of vaccines on mental health. OBJECTIVES: We assessed both individual and spillover effects of COVID-19 vaccination on mental health disorders, and whether effects of individual vaccination varied based on contextual risks indicated by state infection rates and state vaccination rates. METHODS: Using data from the Household Pulse Survey, we assessed 448,900 adults surveyed within approximately the first six months of the U.S. vaccine rollout (February 3 - August 2, 2021). Coarsened exact matching balanced vaccinated and non-vaccinated participants on demographic and economic characteristics. RESULTS: Logistic regression analyses found 7% lowered odds of depression among vaccinated individuals, but no significant difference in anxiety. Reflecting potential spillover effects, state vaccination rates predicted lowered odds of anxiety and depression (1% decrease in odds for each additional 1% of the state population vaccinated). Although state COVID-19 infection rates did not moderate effects of individual vaccination on mental health outcomes, significant interactions indicated that effects of individual vaccination on mental health were stronger in contexts of lower state vaccination rates, and links between state vaccination rates and mental health problems were stronger among unvaccinated individuals. CONCLUSIONS: Results suggest that COVID-19 vaccinations improved the mental health of adults in the U.S., with lower rates of self-reported mental health disorders both among vaccinated individuals themselves and among other individuals living in the same state, particularly when those individuals were not themselves vaccinated. These direct and spillover effects on mental health expand our understanding of the benefits of COVID-19 vaccination for the wellbeing of adults in the U.S.