Safety and Immunogenicity of the BNT162b2 mRNA COVID-19 Vaccine in Adolescents with Juvenile-onset Autoimmune Inflammatory Rheumatic Diseases

Introduction: Safety and immunogenicity data of the vaccine against COVID-19 for adolescents with Juvenile-onset Autoimmune Inflammatory Rheumatic diseases (AIIRD) is currently limited.

Objectives: To prospectively evaluate safety and immunogenicity of the BNT162b2 mRNA vaccine in adolescents with AIIRD treated with immunomodulatory medications.

Methods: This multicenter study examined safety and immunogenicity of the two-dose vaccine in adolescents aged 12-18 years diagnosed with juvenile AIIRD. Safety and post-vaccination COVID-19 infection were evaluated. Post vaccination serum anti-S IgG antibody levels were measured. Seropositivity was defined as IgG ≥15 binding antibody units (AU/ml).

Results: 91 adolescents with AIIRD and 40 controls from 2 countries participated. A total 80.2% (N=70) of patients were on immunomodulatory medications. Post vaccination disease activity remained stable in 98.8% of the patients. Post vaccination treatment change was made in the minority (N=4, 4.6%). Both patients and controls have tolerated the vaccine well, with minimal side effects. No post vaccination COVID-19 was documented in both groups.

Post vaccination seropositivity rate was 100% in both adolescents with AIIRD and controls. However, the level of the S1/S2 antibodies was significantly reduced in adolescents with AIIRD compared to controls (mean± SD 242±136.4 vs 387.8±57.35, P<0.0001).

Conclusion: The COVID-19 vaccine was shown to have excellent safety profile in adolescents with Juvenile-onset AIIRD, with mild post vaccination side effects, similar to the healthy controls. Post vaccination disease activity was mostly kept stable. Immunogenicity was very good in both groups, with significantly higher S antibody titers in the healthy controls. No post vaccination COVID-19 illness was documented.