Trend in the opioid use disorder rate among older beneficiaries by social vulnerability index quartile between 2011 and 2022. Text description: Between 2011 and 2022, the least vulnerable counties (solid line) have the lowest prevalence of opioid use disorder (OUD) among older beneficiaries and the most vulnerable counties (long-dashed line) have the highest prevalence of OUD among older beneficiaries. The gaps across social vulnerability index quartiles had widened between 2011 and 2019 and in 2020, the first year of the COVID-19 pandemic, the gaps narrowed slightly. After 2021, the prevalence of OUD among beneficiaries have increased to the pre-pandemic levels. Notes: COVID-19 = coronavirus disease 2019; SVI = social vulnerability index.