Immunogenicity against the BNT162b2 mRNA COVID-19 Vaccine in Rheumatic Disease Patients Receiving Immunosuppressive Therapy

Objective To investigate the serum total antibody (immunoglobulin M and immunoglobulin G) titre against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein receptor-binding domain following BNT162b2 messenger ribonucleic acid (mRNA) coronavirus disease 2019 (COVID-19) vaccination in Japanese rheumatic disease patients undergoing immunosuppressive therapy. Methods The serum antibody titre against SARS-CoV-2 spike protein was analysed in 123 outpatients with rheumatic diseases at Kagawa University Hospital and 43 healthy volunteers who had received 2 doses of the BNT162b2 mRNA vaccine with at least 14 days elapsing since the second dose. Results The antibody titre in rheumatic disease patients was significantly lower than that in healthy subjects (p