RESULTS
SARS-CoV-2 infection
REACTOGENICITY, ADVERSE EVENTS, SARS-COV-2 INFECTION
Among 2232 participants (1487 NVX-CoV2373 and 745 placebo recipients), the mean (SD) age was 13.8 (1.4) years, 1172 (52.5%) were male, 1660 (74.4%) were White individuals, and 359 (16.1%) had had a previous SARS-CoV-2 infection at baseline. After vaccination, the ratio of neutralizing antibody geometric mean titers in adolescents compared with those in young adults was 1.5 (95% CI, 1.3–1.7). Twenty mild COVID-19 cases occurred after a median of 64 (IQR, 57–69) days of follow-up, including 6 among NVX-CoV2373 recipients (incidence, 2.90 [95% CI, 1.31–6.46] cases per 100 person-years) and 14 among placebo recipients (incidence, 14.20 [95% CI, 8.42–23.93] cases per 100 person-years), yielding a vaccine efficacy of 79.5% (95% CI, 46.8%−92.1%). Vaccine efficacy for the Delta variant (the only viral variant identified by sequencing [n = 11]) was 82.0% (95% CI, 32.4%−95.2%). Reactogenicity was largely mild to moderate and transient, with a trend toward greater frequency after the second dose of NVX-CoV2373. Serious adverse events were rare and balanced between treatments. No adverse events led to study discontinuation.