Systemic and T cell‐associated responses to SARS‐CoV ‐2 immunisation in gut inflammation ( STAR SIGN study): effects of biologics on vaccination efficacy of the third dose of mRNA vaccines against SARS‐CoV ‐2

Summary Background Immunosuppressed patients with inflammatory bowel disease (IBD) experience increased risk of vaccine‐preventable diseases such as COVID‐19. Aims To assess humoral and cellular immune responses following SARS‐CoV‐2 booster vaccination in immunosuppressed IBD patients and healthy controls. Methods In this prospective, multicentre, case–control study, 139 IBD patients treated with biologics and 110 healthy controls were recruited. Serum anti‐SARS‐CoV‐2 spike IgG concentrations were measured 2–16 weeks after receiving a third mRNA vaccine dose. The primary outcome was to determine if humoral immune responses towards booster vaccines differ in IBD patients under anti‐TNF versus non‐anti‐TNF therapy and healthy controls. Secondary outcomes were antibody decline, impact of previous infection and SARS‐CoV‐2‐targeted T cell responses. Results Anti‐TNF‐treated IBD patients showed reduced anti‐spike IgG concentrations (geometric mean 2357.4 BAU/ml [geometric SD 3.3]) when compared to non‐anti‐TNF‐treated patients (5935.7 BAU/ml [3.9]; p < 0.0001) and healthy controls (5481.7 BAU/ml [2.4]; p < 0.0001), respectively. In multivariable modelling, prior infection (geometric mean ratio 2.00 [95% CI 1.34–2.90]) and vaccination with mRNA‐1273 (1.53 [1.01–2.27]) increased antibody concentrations, while anti‐TNF treatment (0.39 [0.28–0.54]) and prolonged time between vaccination and antibody measurement (0.72 [0.58–0.90]) decreased anti‐SARS‐CoV‐2 spike antibodies. Antibody decline was comparable in IBD patients independent of anti‐TNF treatment and antibody concentrations could not predict breakthrough infections. Cellular and humoral immune responses were uncoupled, and more anti‐TNF‐treated patients than healthy controls developed inadequate T cell responses (15/73 [20.5%] vs 2/100 [2.0%]; p = 0.00031). Conclusions Anti‐TNF‐treated IBD patients have impaired humoral and cellular immunogenicity following SARS‐CoV‐2 booster vaccination. Fourth dose administration may be beneficial for these patients.