ABSTRACT
We investigated serum total antibody titers against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein receptor-binding domain after BNT162b2 mRNA vaccination against coronavirus disease 2019 (COVID-19) in Japanese patients taking various immunosuppressive medications for rheumatic disease. In 212 outpatients with rheumatic diseases at Kagawa University Hospital and 43 healthy volunteers (controls), all of whom had received 2 doses of BNT162b2 vaccine, serum antibody titers of SARS-CoV-2 spike protein were analyzed at least 14 days after the second dose. Many of the patients were taking immunosuppressive agents to manage their rheumatic disease. The antibody titers against SARS-CoV-2 spike protein in these patients were significantly lower than those in controls. The analysis of therapeutic agents revealed that the antibody titers in patients treated with rituximab were much lower than those in controls. In patients treated with tacrolimus, baricitinib, azathioprine, mycophenolate mofetil, abatacept, tumor necrosis factor inhibitors, cyclosporine, interleukin-6 inhibitors, methotrexate, or glucocorticoids, antibody titers were moderately lower than those of controls. Interleukin-17 and interleukin-23 inhibitors did not impair the humoral response. In addition, the combination of methotrexate with various immunosuppressive agents reduced titers, although not significantly. In Japanese patients with rheumatic disease, many immunosuppressants impaired the immune response to the BNT162b2 vaccine. The degree of decline in antibody titers differed according to immunosuppressant. When used concomitantly with other immunosuppressants, methotrexate may impair the immune response to the BNT162b2 vaccine. However, immunomodulatory treatments such as interleukin-17 and -23 inhibitors may not attenuate this response in patients with rheumatic disease.