Safety and immunogenicity of the second and third doses of COVID-19
vaccine in adolescents with rheumatic diseases
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.