Antibody response to SARS-CoV-2 mRNA vaccines in patients with rheumatic diseases in Japan: Interim analysis of a multicentre cohort study

Objectives: To evaluate the impact of medication on antibody response to severe acute respiratory syndrome coronavirus-2 mRNA vaccines in Japanese patients with rheumatic diseases. Methods: This prospective multicentre cohort study evaluated the humoral response in 12 different medication groups. Antibody levels before the first vaccination and 3–6 weeks after the second vaccination were measured using the Elecsys Anti-SARS-CoV-2 S assay. Statistical analysis included comparing antibody titres among the different medication groups using the Kruskal–Wallis test followed by the Bonferroni–Dunn test and multiple linear regression analysis. Results: 295 patients were analysed. The seroconversion rate was 92.2% and the median antibody titre was 255 U/ml (interquartile range, 34.1–685) after the second mRNA vaccination. Antibody levels were significantly lower in the groups treated with Tumour necrosis factor inhibitor with methotrexate, abatacept, mycophenolate mofetil (MMF), MMF or mizoribine combined with calcineurin inhibitor, and rituximab or cyclophosphamide compared with those treated with sulfasalazine and/or bucillamine or calcineurin inhibitor (p < 0.01). The correlation between antibody titre and treatment was significant after adjusting for age, gender, and glucocorticoid dose (p < 0.01). Conclusions: Additional early vaccination is required in patients treated with Tumour necrosis factor inhibitor and methotrexate, abatacept, MMF, MMF or mizoribine combined with calcineurin inhibitor and rituximab or cyclophosphamide.