Deficient SARS-CoV-2 hybrid immunity during inflammatory bowel disease

Patients with Inflammatory Bowel Disease (IBD) undergoing immunosuppressive therapies face heightened susceptibility to severe COVID-19. An in-depth understanding of systemic inflammation and cellular immune responses after SARS-CoV-2 vaccination and breakthrough infections (BTI) is required for optimizing vaccine strategies in this population. While the prevalence of high serological responders post- third COVID-19 vaccine dose was lower, and the antibody waning was higher in IBD patients than in healthy donors (HD), IBD patients showed an increase in anti-RBD Wild Type IgG levels and cross-reactive Spike -specific memory B cells following BTI. However, there was no significant enhancement in cellular immune responses against anti-SARS-CoV-2 post-BTI, with responses instead characterized by activation of SARS-CoV-2 specific and also bystander CD8 T cells. These results suggest a complex interaction between chronic inflammation in IBD and the generation of new immune responses, highlighting the need for tailored vaccine regimens and anti-inflammatory therapies to boost cellular immunity against SARS-CoV-2.