Pre-pandemic preventive healthcare engagement and all-cause excess mortality during COVID-19: a county-level ecological study in the United States.

OBJECTIVE: Community resilience during COVID-19 has been linked to social conditions, public-health capacity, and acute-care resources, but the contribution of pre-pandemic realized preventive-care engagement remains incompletely characterized. We examined whether county-level preventive-care engagement was associated with all-cause excess mortality during the COVID-19 period in the United States. METHODS: In this ecological study, county-specific linear trends fitted to the age-adjusted all-cause premature-death/YPLL-75 indicator for 2012-2018 were used to predict expected mortality in 2020-2022. Excess mortality was the percentage difference between observed and expected values; resilience was its negative. We estimated adjusted associations for four preventive-care indicators using five-fold cross-fitted double/debiased machine learning (DML), with learner, fold, state-clustered, external-demographic, and spatial lag/error sensitivities. RESULTS: Across 3,079 counties, mean excess mortality in 2020-2022 was 15.2%. In the primary DML sample (n=2,921), one-standard-deviation higher influenza-vaccination and mammography-screening rates were associated with 0.106 SD (p<0.001) and 0.118 SD (p<0.001) higher resilience, respectively. Preventable hospitalization was negatively associated; primary-care physician density was null. Estimates were stable across all sensitivities, although attenuated after broader demographic adjustment, and influenza vaccination predicted a pre-pandemic placebo outcome. CONCLUSIONS: Pre-pandemic realized preventive-care engagement was associated with lower county-level all-cause excess mortality. These ecological associations are not individual-level causal effects and warrant cautious interpretation given demographic attenuation and the positive placebo. Resilience policy should combine rapid screening and vaccination outreach with sustained, equity-oriented primary-prevention infrastructure.