LAUSR

accination is an effective population strategy for preventing severe COVID-19 disease and reducing infection transmission. 1 The emergence of new variants, particularly more transmissible strains, such as the omicron variants, has resulted in high infection rates in unvaccinated and vaccinated individuals. 2 Concerns about more transmissible variants are especially pertinent for immunosuppressed individuals, in whom vaccines are less immunogenic and less effective. 3 We and others have shown that patients with in fl ammatory bowel disease (IBD) established on immunosuppressive drugs, including in fl iximab (an anti – tumor necrosis factor [TNF] monoclonal antibody) or tofacitinib (a pan – Janus kinase [JAK]-inhibitor), have reduced vaccine-induced humoral responses after 2 and 3 doses of COVID-19 vaccination. 3 – 5 This study aimed to evaluate functional neutralizing antibody responses against the SARS-CoV-2 ancestral and omicron BA.1 variants in an immunosuppressed population of IBD patients.