Abstract Background: Although colorectal cancer (CRC) screening reduces both CRC incidence and CRC-related mortality, it is underutilized, especially among those with lower socioeconomic status (SES) and in racial and ethnic minoritized populations who have been disproportionately impacted by COVID-19. The shift in healthcare priorities to contain and mitigate COVID-19 over the last few years reduced clinical capacity for non-urgent care, including CRC screening. This study aimed to assess the impact of COVID-19 on disparities in CRC screening. Methods: Blue Cross Blue Shield (BCBS) insures approximately one third of Americans. We leveraged BCBS Axis data to examine temporal patterns in CRC screening among individuals aged 45-75 years during 2017-2021, focusing on three periods: 1) first wave of COVID-19 outbreak (Mar-Apr 2020); 2) second wave of COVID-19 outbreak (i.e., the Delta variant, Jan-Feb 2021); and 3) the most recent 2-month interval for which data are available (Nov-Dec 2021). Both invasive and non-invasive CRC screening procedures were identified, and beneficiaries who received screening one year before were excluded. Screening rates within each 2-month interval were calculated. Neighborhood SES was assessed by Social Deprivation Index at the zip code level and categorized into quintiles. Results: The study cohort included 27,628,570 individuals. Throughout the 5-year period, except for the 1st wave of COVID-19 outbreak, screening rates were higher in areas with higher SES. Prior to the pandemic (Jan 2017–Feb 2020), the average bimonthly screening rate in areas with the highest SES was 2.1%, compared to 1.7% in areas with the lowest SES (p <0.001). During the 1st wave of COVID-19 outbreak, screening rate decreased to approximately 0.8% across all SES quintiles. During the 2nd wave of COVID-19 outbreak, screening rates were 1.7% and 1.3% in the highest and lowest SES areas, respectively. For the last 2-month interval in our study period (Nov-Dec 2021), screening rates increased to 2.4% and 1.8% in areas with the highest and lowest SES, respectively. Among 9,565,516 beneficiaries with known race and ethnicity, 8.0%, 11.0%, 3.3% and 0.4% were non-Hispanic Black, Hispanic/Latino, Asian, and Native Americans/Pacific Islanders, respectively. Across all racial and ethnic groups, the average bimonthly screening rate was 1.9% prior to the pandemic, 0.7% in Mar-Apr 2020, 1.5% in Jan-Feb 2021, and 2.1% in Nov-Dec 2021. Conclusion: After the onset of COVID-19, CRC screening rate decreased broadly and reached a similar level in all SES groups in early 2020, but it then recovered at a different pace for individuals with different SES, maintaining and even exacerbating inequities that existed prior to the pandemic. Screening patterns were comparable across different racial and ethnic groups who were privately insured through BCBS. Findings from this very large study may help inform interventions to address social and structural determinants of health and reduce the disproportionate burden of CRC in individuals residing in socially deprived areas. Citation Format: Arfan Siddique, Rong Wang, Jacquelyne Gaddy, Cary Gross, Xiaomei Ma. Impact of COVID-19 on colorectal cancer screening disparities: Results from a large commercially insured population in the United States [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C129.