Role of booster with BNT162b2 mRNA in SARS-CoV-2 vaccination in patients with rheumatoid arthritis.

Only case reports and small clinical series report the effects of booster vaccination with BNT162b2 in patients with rheumatoid arthritis (RA). We studied 200 patients with RA in clinical remission evaluated with the DAS28. All patients were vaccinated for SARS CoV-2 with the BNT162b2 mRNA vaccine. The value of anti-SARS-CoV 2 Spike RBD IgG antibodies was determined at T1 (3 weeks after first vaccination) and T2 (3 weeks after booster). In addition, patients underwent assessment of lymphocyte subpopulations by flow cytometry analysis before starting the vaccination cycle (T0). Furthermore, the serum antibody levels of 96 health care workers (HCWs) were analyzed for comparison. DAS28 values at T0, T1, and T2 indicated remission or low disease activity in all patients. Levels of anti-SARS CoV-2 IgG at T1 were higher in HCWs than in patients' groups: 1562.00 BAU WHO/mL [975.00-1632.00] vs 416.00 BAU WHO/mL [110.00, 1581.00], p <0.001. Anti-SARS COV2 IgG levels at T1 and at T2 were slightly lower in patients taking b/tsDMARDs than in patients under csDMARDs. Regression analysis evidenced age, treatment with abatacept (ABA), JAK inhibitors, and rituximab (RTX) as negative predictors of higher anti-SARS CoV-2 IgG levels at T1. Moreover, treatment with anti-IL6, anti-JAK, and anti-tumor necrosis factor (TNF) emerged as positive predictors of higher levels of anti-SARS CoV-2 IgG at T2. Our data show that despite the booster vaccine with BNT162b2, seroconversion in patients with rheumatoid arthritis is influenced by the background therapy, particularly for patients being treated with ABA and RTX.