ABSTRACT
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 (AIIRD) compared with healthy controls.
Methods : This international prospective study included
adolescents with AIIRD and controls vaccinated with two (AIIRD n=124;
controls n=80) or three (AIIRD 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 titres in a sample from both groups.
Results : The vaccination safety profile was favourable, with
most patients reporting mild or no side-effects. The rheumatic disease
remained stable among 98% and 100% after the second and third doses,
respectively. The two-dose vaccine induced comparable seropositivity
rates among patients (91%) and controls (100%), (p=0.55), which
declined within 6 months to 87% and 100%, respectively (p=0.3), and
increased to 100% in both groups, after the third vaccine dose. The
overall post-vaccination COVID-19 infection rate was comparable between
patients and controls, 47.6% (n=59) and 35% (n=28), respectively;
p=0.5278, with most infections occurring during the Omicron surge. In
relation to the last vaccination, time-to-COVID-19 infection was similar
between patients and controls, at a median of 5.5 vs. 5.2 months,
respectively (log-rank p=0.1555).
Conclusion : The safety profile of three doses of the BNT162b2
mRNA vaccine was excellent, with an adequate humoral response and
similar efficacy among patients and controls. These results support the
recommendation for vaccinating adolescents with juvenile-onset AIIRD
against COVID-19.
Keywords: vaccines, COVID-19, rheumatology, safety,
immunomodulation, adolescent.