Comparative Effectiveness of BNT162b2 and mRNA-1273 Vaccines Against COVID-19 Infection Among Patients With Systemic Autoimmune Rheumatic Diseases on Immunomodulatory Medications.

Objective: To compare the effectiveness of mRNA vaccines (BNT162b2 vs mRNA-1273) against coronavirus disease 2019 (COVID-19) infection among patients with systemic autoimmune rheumatic diseases (SARDs) on immunomodulatory medications.

Methods: We identified patients with SARDs being treated with disease-modifying antirheumatic drugs (DMARDs) and/or glucocorticoids in the Mass General Brigham healthcare system who received either BNT162b2 or mRNA-1273 as their initial vaccine series. Patients were followed until positive SARS-CoV-2 test, death, or February 22, 2022. We compared the risk of breakthrough infection between BNT162b2 and mRNA-1273 vaccine recipients using time-stratified, overlap propensity score (PS)-weighted Cox proportional hazard models.

Results: We identified 9838 patients with SARDs who received BNT162b2 or mRNA-1273. Demographic and clinical characteristics were similar in both groups after overlap weighting: mean age 61 years, 75% female, 52% with rheumatoid arthritis, 74% receiving conventional synthetic DMARDs, and 43% receiving biologic DMARDs. Of 5516 BNT162b2 and 4322 mRNA-1273 recipients, 446 and 329 had a breakthrough infection, respectively. The corresponding time-stratified PS-weighted rate difference of breakthrough infection was 0.71 (95% CI -0.70 to 2.12) per 1000 person-months with a weighted hazard ratio (HR) of 1.12 (95% CI 0.90 to 1.39). When follow-up was censored prior to the Omicron wave, there was a trend toward higher breakthrough risk with BNT162b2 vs mRNA-1273 (weighted HR 1.34, 95% CI 0.91 to 1.98).

Conclusion: Among patients with SARDs, the risk of breakthrough COVID-19 infection is similar after receiving either BNT162b2 or mRNA-1273. Patients with SARDs initiating the vaccine series should be encouraged to receive whichever mRNA vaccine is available.