Background/Purpose: Immunocompromised conditions and/or a history of autoimmune disease were exclusion criteria of the initial SARS-CoV-2 vaccines clinical trials. We assessed the safety and immunogenicity of the mRNA-1273 SARS-CoV-2 vaccine following a two-dose regimen in patients with rheumatic diseases.

Methods: We conducted a prospective, non-randomized, open label, comparative clinical trial (NCT04806113) at two academic centers in Quebec, Canada. Trial participants were adults with either one of the following diagnoses (i) seropositive rheumatoid arthritis (RA) on stable treatment for ≥3 months; (ii) systemic lupus erythematosus (SLE) on stable treatment with mycophenolate mofetil (MMF); (iii) other rheumatic disease receiving ≥10 mg of prednisone; or age/sex matched adults without rheumatic diseases (controls). The primary outcomes included solicited local and systemic reactogenicity adverse events (AEs) in the 7 days after each dose; and unsolicited AEs (including disease flares) in the 28 days following each dose. As our secondary outcome, we assessed the effects of age and treatment on seropositivity, defined by the presence of serum IgG antibody against SARS-CoV-2 spike protein (IgG-S) and its’ receptor binding domain (IgG-RBD), which were measured at baseline and 28±7 days after each dose of the vaccine in a custom automated ELISA platform.

Results: We enrolled 220 participants including 131 RA, 23 SLE, 8 other rheumatic disease, and 58 controls. The mean age (±SD) was 60.4±12.2 and 72% were female. Local and systemic solicited AEs were more frequently reported after the 2nd dose (versus the first dose) in all subjects (94% vs. 86.8%; Δ=7.2%, 95% CI: 2.8%-11.7%), with pain at the injection site being the most common. Swollen joints (solicited adverse event) following both vaccine doses were more frequently reported by RA patients than controls (22.9% vs. 3.4%; Δ=19.5%, 95%CI: 10.9%-28%); however, we saw no clear increase in disease activity scores post-vaccination. No serious adverse events were attributed to the vaccine. After the 1st dose, seropositivity for both IgG-S and IgG-RBD was 100% in controls, but only 67.7% in RA, 34.8% in SLE, and 87.5% in other rheumatic diseases. After the 2nd dose, seropositivity for both IgG-S and IgG-RBD remained 100% in controls and increased to 88.5% in RA and 78.3% in SLE and persisted at 87.5% in other rheumatic diseases. In RA, seropositivity post-2nd dose in older (65+) versus younger age was similar (88% vs. 88.8%; Δ=-0.8%, 95%CI: -12.1%-10.6%). People on rituximab (9% vs. 88%, Δ= -78.8%, 95%CI: -98.1% to -59.5%) or MMF (39% vs. 58%, Δ= -19.3%, 95%CI: -36.4% to -2.2%) had lower humoral responses than patients not on those drugs post-two vaccine doses.

Conclusion: In this prospective study, the mRNA-1273 SARS-CoV-2 vaccine was not associated with severe disease flares. MMF and rituximab were associated with a reduction in vaccine-induced humoral responses.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/covid-19-vaccine-in-immunosuppressed-adults-with-autoimmune-diseases/