ABSTRACT
BACKGROUND AND AIMS: Patients with inflammatory bowel disease (IBD) have an attenuated response to initial COVID-19 vaccination. We sought to characterise the impact of IBD and its treatment on responses after third vaccine against SARS-CoV-2. METHODS: Prospective multicentre observational study of patients with IBD (n=202) and healthy controls (HC, n=92). Serological response to vaccination was assessed by quantification of anti-spike protein (SP) immunoglobulin (Ig)G levels (anti-SPIgG) and in-vitro neutralisation of binding to Angiotensin-Converting-Enzyme (ACE2). Peripheral blood B-cell phenotype populations were assessed by flow cytometry. SARS-CoV-2 antigen specific B-cell responses were assessed in ex-vivo culture. RESULTS: Median anti-SP IgG post-third vaccination in our IBD cohort is significantly lower than HCs (7,862 versus 19,622 AU/mL, p <0.001) as is ACE2 binding inhibition (p <0.001). IBD patients previously infected with COVID-19 (30%) have similar quantitative antibody response as HCs previously infected with COVID-19 (p = 0.12). Lowest anti-SP IgG titres and neutralisation are seen in IBD patients on anti-TNF agents, without prior COVID-19 infection but all IBD patients show attenuated vaccine response compared to HCs. Patients with IBD have reduced memory B-cell populations and attenuated B-cell responses to SARS-CoV-2 antigens if not previously infected with COVID-19 (p = 0.01). Higher anti-TNF drug levels and zinc levels < 65ng/ml are associated with significantly lower serologic response. CONCLUSIONS: Patients with IBD have an attenuated response to three doses of SARS-CoV-2 vaccine. Physicians should consider patients with higher anti-TNF drug levels and/or zinc deficiency as potentially at higher risk of attenuated response to vaccination.