Humoral Response of Patients With Autoimmune Rheumatic Disease to BNT162b2 Vaccine: A Retrospective Comparative Study

Objective The effectiveness and safety of SARS-CoV-2 vaccines in patients with autoimmune rheumatic diseases (ARDs) treated with immunomodulators remain uncertain. Therefore, this study aimed to evaluate whether the humoral immune response to the BNT162b2 vaccine differs between patients without and with ARDs treated with immunomodulators. Methods We retrospectively reviewed 3208 electronic medical records from the database of the Hamad Medical Corporation (HMC) outpatient rheumatology clinics to capture patients with ARDs and control patients without autoimmune inflammatory diseases. All patients who were SARS-CoV-2 infection-naïve, had received two doses of BNT162b2 vaccination, and had been serologically tested using Elecsys® anti-SARS-CoV-2 S immunoassays (Roche Holdings AG, Basel, Switzerland), were included in the analysis. Patients with ARD were classified into six subgroups according to the received ARD immunomodulators: methotrexate monotherapy (MTXM), a combination of conventional synthetic disease-modifying antirheumatic drugs (Cs-DMARDs), tumor necrosis factor inhibitor (TNF-i), rituximab, interleukin-6 inhibitor (IL6-i), and Janus kinase inhibitor (JAK-i). Samples with an anti-SARS-CoV-2 S titer of <0.8 and <132 binding antibody unit (BAU)/mL were defined as negative and poor seroconversion, respectively. The overall mean of anti-SARS-CoV-2 S titer and its level at <0.8 and <132 were compared between the six subgroups of patients with ARD and the controls by performing an unpaired t-test and Chi-squared or Fisher's exact test as appropriate. Results The mean (SD) age of 110 patients with ARDs and 20 controls was 47.1 (12) and 59.3 (8.9) years (P < 0.001), respectively, and women predominated both groups (60% vs. 75%, P = 0.20). The most frequently prescribed Cs-DMARDs was methotrexate in 50 (45.5%) patients, followed by TNF-i in 46 (41.8%), rituximab in 20 (18.2%), JAK-i in 12 (10.9%), and IL6-i in 7 (6.4%) patients. The mean (SD) anti-SARS-CoV-2 S antibody titer of only the rituximab subgroup significantly differed from the controls (P = 0.012). Conclusion The most prevalent ARD immunomodulators (Cs-DMARDs, TNF-i, JAK-i, and IL6-i) were associated with comparable seroconversion rates to the BNT162b2 vaccine. In comparison, rituximab was significantly associated with decreased immunogenicity.