ABSTRACT
Objectives: Our aims were to evaluate Systemic Lupus Erythematosus (SLE) disease activity and SARS-CoV-2 specific immune responses after BNT162b2 vaccination. Methods: In this prospective study, disease activity and clinical assessments were recorded from the first dose of vaccine, until day 15 after the second dose in 126 SLE patients. SARS-CoV-2 antibody responses were measured against wild-type spike antigen while serum-neutralizing activity was assessed against the SARS-CoV-2 historical strain and variants of concerns (VOCs). Vaccine-specific T-cell responses were quantified by Interferon (IFN)-gamma; release assay after the second dose. Results: BNT162b2 was well tolerated and no statistically significant variations of BILAG and SLEDAI scores were observed throughout the study in SLE patients with active and inactive disease at baseline. Mycophenolate Mofetil (MMF) and Methotrexate (MTX) treatments were associated with drastically reduced BNT162b2 antibody-response (beta=-78; p=0.007, beta=-122; p<0.001, respectively). Anti-spike antibody response was positively associated with baseline total IgG serum levels, naive B cell frequencies (beta=2; p=0.018, beta=2.5; p=0.003) and SARS-CoV-2-specific T cell response (r=0.462; p=0.003). In responders, serum neutralization activity decreased against VOCs bearing the E484K mutation but remained detectable in a majority of patients. Conclusion: MMF, MTX and poor baseline humoral immune status, particularly: low naive B cell frequencies, are independently associated with impaired BNT162b2 mRNA antibody response, delineating SLE patients who might need adapted vaccine regimens and follow-up.