Humoral immunity improves with a booster dose of SARS-CoV-2 vaccine in patients with inflammatory bowel disease on immunosuppressants

Abstract Purpose Patients with inflammatory bowel disease (IBD) are often treated with immunosuppressants and immunobiologicals. We evaluated the humoral response after vaccination against SARS-Cov-2 in patients with IBD compared to a healthy population Methods Patients with IBD, enrolled in a tertiary outpatient unit, were followed-up with serial blood collections between September 2021 and September 2022. IgG antibody titers against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were measured before and one month after the administration of the two doses of the different vaccination regimens. The results were compared with those of a healthy control group obtained during the same period. Results Mean pre-vaccination antibody titers were 430.3 AU/mL and 90.5 AU/mL in the IBD (46 participants) and control (92 participants) groups, respectively. After two doses of vaccine, the titers significantly increased in both groups (IBD, 8038.4 AU/mL; control, 7697.5 AU/mL; p < 0.001). One month after the second dose, no significant difference was observed between the two groups (p = 0.731). In the IBD group, there was a difference between vaccination schemes, with higher titers in those who received Pfizer, younger patients (p < 0.005), and those with a previous COVID-19 infection (p < 0.012). Conclusion The use of immunosuppressants and immunobiologicals did not affect the overall humoral response to the COVID-19 vaccine in patients with IBD. However, specific vaccine regimens, age, and previous coronavirus infection significantly affected the response. This study reinforces the positive impact of booster doses and safety of SARS-CoV-2 vaccination.