Among veterans with inflammatory bowel disease (IBD) and diverse exposure to immunosuppressive agents, full vaccination for SARS-CoV-2 is significantly associated with reduced infection, according to a study in Gastroenterology.
Researchers identified a national cohort of patients with IBD from the Veterans Health Administration (VHA) to evaluate the effectiveness of the SARS-CoV-2 vaccination in the IBD population and the potential impact of immunosuppressive medications.
The retrospective cohort study included VHA data from December 18, 2020, when the VHA began providing COVID-19 vaccinations to patients, through April 20, 2021. Eligible participants were aged ≥18 years and had not been previously diagnosed with SARS-CoV-2 infection in the VHA system. Included participants were also taking an IBD medication, and had at least 6 months of VHA outpatient visit data before the index date. IBD medications included 5-aminosalicylic acid (ASA), thiopurines, anti–tumor necrosis factor (TNF) biologic agents, vedolizumab, ustekinumab, tofacitinib, methotrexate, and corticosteroids.
The final cohort included 14,697 patients. A majority of participants had ulcerative colitis (61.8%), with 54.8% taking 5-ASA alone, 19.9% taking anti-TNFs alone, and 10.7% taking thiopurines. Unvaccinated participants (n=7376; median age, 64 years; 91.7% male; 80.3% White) had fewer comorbidities compared with those who were vaccinated (n=7321; median age, 71 years; 92.6% male; 80.5% White; each medical comorbidity P <.001).
About 45% of patients received the Pfizer vaccine, with the rest of the cohort receiving the Moderna vaccine. No differences in effectiveness were observed between the vaccines.
After a median follow-up of 123 days (interquartile range [IQR], 70-123 days), unvaccinated participants had the numerically highest rate of SARS-CoV-2 infection (197 patients; 1.34%). In comparison, after a median follow-up of 20 days (IQR, 14-21 days) 14 (0.28%) SARS-CoV-2 infections were found among patients with partially vaccinated status. After a median follow-up of 38 days (IQR, 20-55 days) 7 (0.11%) infections were observed in participants who were fully vaccinated.
In the inverse probability weighted–adjusted model, full vaccination was associated with a 69% reduction in the hazard of infection (hazard ratio, 0.31; 95% CI, 0.17-0.56; P <.001) relative to unvaccinated participants. The corresponding vaccine effectiveness was 25.1% for participants with partial vaccination status and 80.4% for those with full vaccination status.
Among several limitations, the study authors noted the possibility of residual confounding. Additionally, the study cohort was comprised primarily of older men, limiting external validity. Finally, patients are not proactively screened for SARS-CoV-2 in the VHA and are tested when symptomatic or as a preventive measure, such as before an elective procedure.
“This study supports the effectiveness of vaccination in patients with IBD taking diverse immunosuppressive agents and may allay fears in this regard,” stated the researchers.
Disclosures: One of the study authors declared affiliations with pharmaceutical companies. Please see the original reference for a full list of disclosures.
Khan N, Mahmud N. Effectiveness of SARS-CoV-2 vaccination in a Veterans Affairs cohort of inflammatory bowel disease patients with diverse exposure to immunosuppressive medications. Gastroenterol. Published online May 25, 2021. doi: 10.1053/j.gastro.2021.05.044