Safety of and antibody response to the BNT162b2 COVID-19 vaccine in adolescents and young adults with underlying disease

BACKGROUND: Data are limited regarding the safety of and antibody response to the BNT162b2 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger ribonucleic acid vaccine in adolescents and young adults with underlying disease. METHODS: This prospective observational study enrolled patients age 12–25 years with chronic underlying disease who received 2 doses of BNT162b2. A 18-item questionnaire was used to assess adverse events within 7 days post-vaccination, and data regarding severe adverse events were collected from electronic medical records. An antibody titer for the receptor-binding domain of the spike protein in SARS-CoV-2 was used to assess antibody response after the second vaccine dose. RESULTS: Study participants were 429 patients (241 [56.2%] age 12–15 years; 188 [43.8%] age 16–25 years). The most common underlying diseases were genetic or chromosomal abnormalities and/or congenital anomalies, followed by endocrine or metabolic diseases; 32% of participants were immunocompromised. Severe adverse events were observed after the second dose in 1 (0.4%) patient age 12–15 years and in 2 (1.1%) patients age 16–25 years; all patients recovered. Seropositivity after the second vaccine dose was 99.0%. The geometric mean antibody titer was higher in patients age 12–15 years versus 16–25 years (1603.3 [1321.8–1944.7] U/mL vs. 949.4 [744.2–1211.0] U/mL). Compared with immunocompetent patients, immunocompromised patients had a lower antibody titer (2106.8 [1917.5–2314.7] U/mL vs. 467.9 [324.4–674.8] U/mL). CONCLUSIONS: Vaccination with BNT162b2 was acceptably safe and immunogenic for adolescents and young adults with underlying disease.