Background: To explore the long-term safety and dynamics of the immune response induced by the second and third doses of the BNT162b2 mRNA COVID-19 vaccine in adolescents with juvenile-onset autoimmune inflammatory rheumatic diseases (AIIRDs) compared with healthy controls.
Methods: This international prospective study included adolescents with AIIRDs and controls vaccinated with two (AIIRDs n = 124; controls n = 80) or three (AIIRDs n = 64; controls n = 30) doses of the BNT162b2 vaccine, evaluated for vaccine side-effects, disease activity, COVID-19 breakthrough infection rates and severity, and anti-spike S1/S2 IgG antibody titers in a sample from both groups.
Results: The vaccination safety profile was favorable, with most patients reporting mild or no side-effects.