Comparison of Unemployment-Related Health Insurance Coverage Changes in Medicaid Expansion vs Nonexpansion States During the COVID-19 Pandemic

IMPORTANCE: The COVID-19 pandemic has been associated with increased unemployment rates and long periods when individuals were without health insurance. Little is known about how Medicaid expansion facilitates Medicaid enrollment as a buffer to coverage loss owing to unemployment. OBJECTIVE: To compare changes in health insurance coverage status associated with pandemic-related unemployment among previously employed adults in states that have vs have not expanded Medicaid eligibility. DESIGN, SETTING, AND PARTICIPANTS: This cohort study included US adults aged 27 to 64 years who were employed at baseline in the 2020 to 2021 Current Population Survey’s Annual Social and Economic Supplement, which included calendar years 2019 to 2020 (32 462 person-years). Data analyses were conducted between November 2021 and April 2022. EXPOSURES: Job loss (ie, new unemployment) experienced during 2020. MAIN OUTCOMES AND MEASURES: Primary outcomes were coverage status (ie, uninsured status) and source of coverage (ie, employer sponsored, marketplace, and Medicaid). Using 2-way person-by-year fixed-effects regression models, changes in coverage status associated with unemployment in states that expanded Medicaid were compared with states that did not expand Medicaid. Additional analyses were performed based on prepandemic coverage status. RESULTS: The cohort included 16 231 adults (mean age, 46.8 [95% CI, 46.6-47.0] years; 51.6% women). New unemployment was associated with an increase of 2.9 (95% CI, 1.1-4.6) percentage points (P = .002) in the proportion of uninsured adults in Medicaid expansion states and an increase of 10.7 (95% CI, 2.4-18.9) percentage points (P = .01) in nonexpansion states. Workers were 5.4 (95% CI, 1.9-8.9) percentage points (P = .003) more likely to enroll in Medicaid after a job loss if they lived in a Medicaid expansion state compared with workers experiencing job loss in nonexpansion states. CONCLUSIONS AND RELEVANCE: In this cohort study of US adults, unemployment-related Medicaid enrollment was more frequent in Medicaid expansion states during the COVID-19 pandemic. Medicaid expansion led to a smaller increase in uninsured adults because those who lost private insurance coverage (eg, employer sponsored) appeared more able to transition to Medicaid after job loss.