The California Bridge Program supports expansion of medications for opioid use disorder (MOUD) in emergency departments (EDs) and hospital inpatient units across the state. Here, we describe the change in activity before and after the coronavirus disease 2019 (COVID-19) California statewide shutdown. Of the 70 participating hospitals regionally distributed across California, 52 report MOUD-related activity monthly. We analyzed data on outcomes of OUD care and treatment: identification of OUD, acceptance of referral, receipt of buprenorphine prescription, administration of buprenorphine, and follow-up linkage to outpatient OUD treatment, from May 2019 to April 2020. In estimating the expected number of patients who met each outcome in April 2020, we found decreases in the expected to observed number of patients across all outcomes (all p-values<0.002): 37% (from 1053 to 667) decrease in the number of patients identified with OUD, 34% (from 632 to 420) decrease in the number of patients who accepted a referral, 48% (from 521 to 272) decrease in the number of patients who were prescribed buprenorphine, 53% (from 501 to 234) decrease in the number of patients who were administered buprenorphine, and 33% (from 416 to 277) decrease in the number of patients who attended at least one follow-up visit for addiction treatment. The COVID-19 California statewide shutdown was associated with an abrupt and large decrease in the progress toward expanded access to OUD treatment.