Immunogenicity and Safety of Standard and Third Dose SARS-CoV-2 Vaccination in Patients on Immunosuppressive Therapy

Immunogenicity and safety following standard SARS-CoV-2 vaccination in patients with immune-mediated inflammatory diseases (IMID) are poorly characterized, and data on third dose vaccination are lacking. Study aim was to evaluate serological response and adverse events following standard and third dose SARS-CoV-2 vaccination in IMID-patients on immunosuppressive therapy. Adult patients on immunosuppressive therapy for rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, Crohn's disease, ulcerative colitis, and healthy controls receiving standard two dose SARS-CoV-2 vaccination, were included in this prospective observational study. Analyses of antibodies to the receptor-binding domain (RBD) of the SARS-COV-2 spike protein were performed prior to, and 2-4 weeks after vaccination. Poorly responding patients were allotted a third vaccine dose. 1505 (91%) patients and 1096 (98%) healthy controls (p