Many individuals do not receive recommended vaccines, increasing infectious disease morbidity and mortality. It is unknown whether the financial practices of US healthcare institutions contribute to vaccine hesitancy. To determine whether medical debt is associated with low vaccine uptake. Cross-sectional analysis of the association between medical debt and vaccine receipt. 56,373 adult participants in the 2021-2022 National Health Interview Survey. Presence of medical debt at the time of survey administration. We used logistic regression models to assess whether medical debt was associated with recent vaccine receipt, adjusting for sociodemographic, health, and access-to-care variables. We performed a sensitivity analysis restricted to individuals with health insurance and conducted a falsification test of the hypothesis that current medical debt would not be associated with remote prior vaccination (i.e., > 1year prior, likely before debt acquisition). Individuals with medical debt were less likely than those without such debt to receive any recent vaccine (adjusted odds ratio [aOR] 0.83, 95% confidence interval [CI] 0.76-0.91), including influenza vaccination (aOR 0.83, 95% CI 0.75-0.91) or COVID-19 vaccination (aOR 0.79, 95% CI 0.69-0.91). Analyses limited to insured individuals had similar findings (aOR for any recent vaccination 0.79, 95% CI 0.72-0.88). In the falsification test, current medical debt was not associated with remote prior vaccination (aOR 1.04, 95% CI 0.93-1.16). Current medical debt is associated with lower likelihood of recent vaccine receipt in both insured and uninsured individuals. Policies that minimize medical debt may improve vaccine coverage.