Effectiveness in adolescents 12 years through 17 years of age is based on a comparison of immune responses in this age group to adults 18 years through 25 years of age.
Study 1 is an ongoing Phase 3 multicenter, randomized, observer-blinded, placebo-controlled study that included 2,247 participants 12 through 17 years of age in the United States. Participants were randomized in a 2:1 ratio to receive two doses of the Novavax COVID-19 Vaccine, Adjuvanted or placebo 3 weeks apart. The study excluded participants who were significantly immunocompromised due to immunodeficiency disease; had active cancer on chemotherapy; had received chronic immunosuppressive therapy or had received immunoglobulin or blood-derived products within 90 days; were pregnant or breastfeeding; or had a history of laboratory-confirmed diagnosed COVID-19. Participants with clinically stable underlying comorbidities and participants with well-controlled HIV infection were included.
In Study 1, an analysis was conducted of SARS-CoV-2 neutralizing antibody titers 14 days after Dose 2 in a subset of adolescents 12 through 17 years of age and participants 18 through 25 years of age from the adult main study. Noninferior immune responses as assessed by geometric mean titers and seroconversion rates were demonstrated in a comparison of adolescents 12 through 17 years of age to participants 18 through 25 years of age (Table 6).
|Assays||TimePoint||12 Years Through 17 Years||18 Years Through 25 Years||12 Years Through 17 Years/18 Years Through 25 Years|
|GMT *(95% CI)n=390||GMT *(95% CI)n=415||GMR †(95% CI)||Met NoninferiorityCriteria ‡|
|CI = Confidence interval; GMR = Geometric mean ratio; GMT = Geometric mean titer; SCR = Seroconversion rate|
|SARS-CoV-2 wild-typemicroneutralization assay (1/dilution)§||14 daysafterDose 2||3859.6 (3422.8, 4352.1)||2611.8 (2367.4, 2881.5)||1.47 (1.26, 1.72)3||Yes|
|SCR%¶(95% CI) n=385||SCR%¶(95% CI)n=414||Difference inSCR%# (95% CI)|
|98.7 (97.0, 99.6)||99.8 (98.7, 100.0)||-1.04 (-2.75, 0.20)|
A descriptive efficacy analysis evaluating PCR-confirmed symptomatic mild, moderate or severe COVID-19 cases was performed in 1,799 participants who were included in the per-protocol efficacy (PP-EFF) Analysis Set, which required receipt of two doses (Dose 1 on day 0; Dose 2 on day 21), no exclusionary protocol deviation(s), and no evidence of SARS-CoV-2 infection through 6 days after the second dose. In the PP-EFF Analysis Set, 47.2% were female; 15.8% were Hispanic or Latino; 76.1% were White, 12.9% were Black or African American, 1.1% were American Indian or Alaska Native, 3.6% were Asian, and 5.6% were multiracial. The median age of participants was 14 years (range 12-17 years). Of the study participants in the PP-EFF Analysis Set, 25.3% were obese. Between participants who received the Novavax COVID-19 Vaccine, Adjuvanted and those who received placebo, there were no notable differences in demographics. The median interval between doses of study vaccine was 22 days (range 14-43). As of the August 9, 2021, data cutoff date, the PP-EFF Analysis Set had a median follow-up of 67 days post-Dose 2 during the pre-crossover period.
Vaccine efficacy in participants without evidence of SARS-CoV-2 infection through 6 days after the second dose is presented in Table 7. Based on data accrued through August 9, 2021, the efficacy of the Novavax COVID-19 Vaccine, Adjuvanted to prevent PCR-confirmed symptomatic mild, moderate or severe COVID-19 from 7 days after Dose 2 was 78.29% (95% CI: 37.55%, 92.45%). No cases of moderate or severe COVID-19 were reported in participants who had received the Novavax COVID-19 Vaccine, Adjuvanted or placebo.
|Subgroup||Novavax COVID-19 Vaccine, Adjuvanted||Placebo||Vaccine Efficacy (95% CI) (%)|
|Partici-pantsN||COVID-19 Cases †n (%)||Mean Incidence Rate Per 100 Person-Years||Partici-pantsN||COVID-19 Cases †n (%)||Mean Incidence Rate Per 100 Person-Years|
|Primary efficacy endpoint|
|All participants||1205||5 (0.4)||2.69||594||11 (1.9)||12.38||78.29(37.55, 92.45)‡|
|Mild||–||5 (0.4)||–||–||11 (1.9)||–||–|
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