Immunosuppressive therapy and humoral response to third mRNA COVID-19 vaccination with a six-month interval in rheumatic disease patients

Objectives: To evaluate the long-term impact of immunosuppressive therapeutic agents on antibody response to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) mRNA vaccination in patients with autoimmune rheumatic diseases (AIRD) in order to propose a strategy for annual vaccination. Methods: This prospective multicentre cohort study evaluated the humoral response to second and third BNT162b2 and/or mRNA-1273 vaccines in 382 Japanese AIRD patients classified into 12 different medication groups and in 326 healthy controls (HCs). The third vaccination was administered six months after the second vaccination. Antibody titres were measured using the Elecsys Anti-SARS-CoV-2 S assay. Results: The seroconversion rate and antibody titres were lower in AIRD patients than in HCs 3–6 weeks after the second vaccination and 3–6 weeks after the third vaccination. Seroconversion rates were <90% after the third vaccination in patients receiving mycophenolate mofetil and rituximab. Antibody levels after the third vaccination were significantly lower in the groups prescribed TNF inhibitor with or without methotrexate, abatacept and rituximab or cyclophosphamide than those of HCs in a multivariate analysis adjusting for age, sex, and glucocorticoid dosage. The third vaccination induced an adequate humoral response in patients treated with sulfasalazine, bucillamine, methotrexate monotherapy, iguratimod, interleukin-6 inhibitors or calcineurin inhibitors including tacrolimus. Conclusions: Repeated vaccinations in many immunosuppressed patients produced antibody responses similar to those observed in HCs. In contrast, annual vaccination in patients receiving TNF inhibitors, abatacept, mycophenolate mofetil and rituximab may require caution.