Using the synthetic control method to determine the impact of state-level mask mandates on COVID-19 fatality rates

Abstract

ABSTRACT The purpose of the present study is to determine if state-level mask mandates significantly reduced COVID-19 fatality rates. Using weekly data for the period 22 January 2020 to 1 February 2022 and a synthetic control method, results indicated that mask mandates were associated with reductions in COVID-19 fatalities. In both California and Washington, mask mandates were associated with a reduction in COVID-19 fatality rates, especially after COVID-19 vaccines became readily available in April of 2021. In Oregon, there was no statistically significant relationship between mask mandates and COVID-19 fatality rates. To test the robustness of these results, a random effects model was also estimated, and it was also found that mask mandates were associated with a significant reduction in COVID-19 fatality rates. Findings also indicated that states with larger elderly populations and larger populations of African-Americans had significantly higher COVID-19 fatality rates.