Effectiveness of SARS-CoV-2 vaccination in a Veterans Affairs Cohort of Inflammatory Bowel Disease Patients with Diverse Exposure to Immunosuppressive Medications

Khan, Nabeel; Mahmud, Nadim

Background and Aims Vaccination against SARS-CoV-2 has rapidly expanded, however clinical trials excluded patients taking immunosuppressive medications such as those with inflammatory bowel disease (IBD). Therefore, we explored real-world effectiveness of COVID-19 vaccination on subsequent infection in IBD patients with diverse exposure to immunosuppressive medications. Methods This was a retrospective cohort study of patients in the Veterans Health Administration with IBD diagnosed prior to 12/18/20, the start date of the VHA patient vaccination program. IBD medication exposures included 5-aminosalicylic acid, thiopurines, anti-tumor necrosis factor biologic agents, vedolizumab, ustekinumab, tofacitinib, methotrexate, and corticosteroid use. We used inverse probability weighting and Cox regression with vaccination status as a time-updating exposure, and computed vaccine effectiveness from incidence rates. Results The cohort comprised 14,697 patients, 7,321 of whom received at least one vaccine dose (45.2% Pfizer, 54.8% Moderna). The cohort had median age 68 years, was 92.2% male, 80.4% white, and 61.8% with ulcerative colitis. In follow-up data through April 20, 2021, unvaccinated individuals had the highest raw proportion of SARS-CoV-2 infection (197 [1.34%] versus 7 [0.11%] fully vaccinated). Full vaccination status, but not partial vaccination status, was associated with a 69% reduced hazard of infection relative to an unvaccinated status (hazard ratio [HR] 0.31, 95% confidence interval [CI] 0.17-0.56, p<0.001), corresponding to an 80.4% effectiveness. Conclusion Full vaccination (>7 days after the 2nd dose) against SARS-CoV-2 infection has an approximately 80.4% effectiveness in a broad IBD cohort with diverse exposure to immunosuppressive medications. These results may serve to increase patient and provider willingness to pursue vaccination in these settings.