BackgroundThe COVID-19 pandemic spurred relaxation of opioid treatment program (OTP) in-person daily dosing requirements. This policy change was met with widespread enthusiasm by patients and providers and did not increase illicit opioid use, overdose, or medication diversion. However, it is not known whether the policy change was effective at mitigating the COVID-19 public health emergency among people with opioid use disorder (OUD) receiving treatment at OTPs.ObjectiveTo evaluate the impact of treatment at OTPs on rates of COVID-19 infections and complications.DesignProspective cohort from 4/1/2020 to 3/31/2021.ParticipantsOregon Medicaid beneficiaries with an OUD diagnosis.Main MeasuresThe exposure was time-varying treatment for OUD, including (1) medication treatment at an OTP, (2) office-based opioid medication treatment (OBOT), (3) other treatment without medications for OUD, or (4) no treatment. Outcomes were COVID-19 diagnoses, COVID-related emergency department visits, and COVID-related hospitalizations.ResultsParticipants (N = 24,654) averaged 39 years old, most were female (53%), White (84%), and non-Hispanic (88%). Adjusted for characteristics and comorbidities, OTP patients demonstrated significantly reduced risk of COVID-19 diagnoses compared to all other groups: a 37% reduction compared to OBOT, a 52% reduction compared to non-MOUD treatment, and a 37% reduction compared to no OUD treatment. OTP treatment was also associated with a 40% risk reduction of COVID-related ED visits compared to OBOT, a 56% reduction compared to non-MOUD treatment, and a 46% risk reduction compared to no treatment. For inpatient stays, there was not a significant difference between OTP and OBOT treatment or no treatment, but OTP treatment was associated with a 64% risk reduction compared to non-MOUD treatment.ConclusionsLower risks of COVID-19 diagnoses and complications were observed among people with OUD receiving treatment at OTPs compared to other forms of treatment or no treatment.