ImportanceMedicaid coverage loss can substantially compromise access to and affordability of health care for dual-eligible beneficiaries. The extent to which this population lost Medicaid coverage before and during the COVID-19 public health emergency (PHE) and the characteristics of beneficiaries more at risk for coverage loss are currently not well known.ObjectiveTo assess the loss of Medicaid coverage among dual-eligible beneficiaries before and during the first year of the PHE, and to examine beneficiary-level and plan-level factors associated with heightened likelihood of losing Medicaid.Design, Setting, and ParticipantsThis repeated cross-sectional study used national Medicare data to estimate annual rates of Medicaid loss among dual-eligible beneficiaries before (2015 to 2019) and during the PHE (2020). Individuals who were dual eligible for Medicare and Medicaid at the beginning of a given year and who continuously received low-income subsidies for Medicare Part D prescription drug coverage were included in the sample. Multivariable regression models were used to examine beneficiary-level and plan-level factors associated with Medicaid loss. Data analyses were conducted between March 2023 and October 2023.ExposureOnset of PHE.Main Outcomes and MeasuresLoss of Medicaid for at least 1 month within a year.ResultsSample included 56 172 736 dual-eligible beneficiary-years between 2015 and 2020. In 2020, most dual-eligible beneficiaries were aged over 65 years (5 984 420 [61.1%]), female (5 868 866 [59.9%]), non-Hispanic White (4 928 035 [50.3%]), full-benefit eligible (6 837 815 [69.8%]), and enrolled in traditional Medicare (5 343 537 [54.6%]). The adjusted proportion of dual-eligible beneficiaries losing Medicaid for at least 1 month increased from 6.6% in 2015 to 7.3% in 2019 and then dropped to 2.3% in 2020. Between 2015 and 2019, dual-eligible beneficiaries who were older (ages 55-64 years: −1.4%; 95% CI, −1.8% to −1.0%; ages 65-74 years: −2.0%; 95% CI, −2.5% to −1.5%; ages 75 and older: −4.5%; 95% CI, −5.0% to −4.0%), disabled (−0.8%; 95% CI, −1.1% to −0.6%), and in integrated care programs were less likely to lose Medicaid. In 2020, the disparities within each of these demographic groups narrowed significantly. Notably, while Black (0.6%; 95% CI, 0.2% to 0.9%) and Hispanic (0.7%; 95% CI, 0.3% to 1.2%) dual-eligible beneficiaries were more likely to lose Medicaid than their non-Hispanic White counterparts between 2015 and 2019, such gap was eliminated for Black beneficiaries and narrowed for Hispanic beneficiaries in 2020.Conclusions and RelevanceDuring the PHE, Medicaid coverage loss declined significantly among dual-eligible beneficiaries, and disparities were mitigated across subgroups. As the PHE unwinds, it is crucial for policymakers to implement strategies to minimize Medicaid coverage disruptions and racial and ethnic disparities, especially given that loss of Medicaid was slightly increasing over time before the PHE.