Safety, Immunogenicity and Efficacy of the Pfizer Vaccine Amongst 686 Patients with Autoimmune Inflammatory Rheumatic Diseases

June 16, 2021

Israel has been a model for vaccination success against COVID-19, with over 56% of the country being fully vaccinated. On Monday, June 13, Israeli researchers published the findings of the largest observational prospective study confirming the immunogenicity, efficacy, and safety of the Pfizer vaccine amongst 686 patients with autoimmune inflammatory rheumatic diseases (AIIRD). 

Rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis, systemic lupus erythematosus (SLE), systemic vasculitis, Behcet’s disease, and Susac syndrome were included under the umbrella of AIIRD. Patients were instructed to continue all medications besides rituximab (pending physician’s recommendations). 

Healthcare providers made up the majority of the control group (121 participants), and all participants were given a complete dose of the Pfizer vaccine three weeks apart. Post-vaccination status and activity were assessed within 2-6 weeks following the second dose.

While the immunogenicity rates (immune response towards a vaccine over a long period of time) amongst those on immunosuppressive therapies such as rituximab and glucocorticoids were lower than average, there were no post-vaccination symptomatic COVID-19 cases amongst those with AAIRD. This data is concurrent with available data recorded in the US and short-term efficacy research published by the American College of Rheumatology.

The prevalence of adverse events was also similar between patients with AIIRD and the control group. Post-vaccination disease remained relatively stable in the majority of patients with AIIRD, and adverse events were typically mild in nature. Major adverse events included herpes zoster (6 cases), uveitis (2), pericarditis (1), and two deaths several weeks after receiving the second dose. 

AIIRD patients exhibited a reduced antibody production rate of 86% following the vaccine compared to 100% in controls. Patients with psoriatic arthritis, axial spondyloarthritis, systemic lupus erythematosus (SLE), and systemic vasculitis demonstrated a seropositivity rate (positive serum reaction when testing for antibodies) above 90%. The seropositivity rate amongst patients with rheumatoid arthritis was 82.1%. “The seropositivity rate in patients vaccinated within 6 months after rituximab treatment was below 20% but increased to about 50% in patients vaccinated 1 year after rituximab treatment.”