Novavax reports 80% efficacy in adolescent COVID-19 vaccine trial
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Novavax on Thursday announced that its COVID-19 vaccine was around 80% effective among adolescents aged 12 to 17 years in a phase 3 trial.
The company, which recently asked the FDA to authorize the vaccine for emergency use in adults, said it would supplement its global filings with data from the pediatric trial sometime in the first quarter of 2022.
Novavax’s protein-based vaccine differs from Pfizer’s messenger RNA vaccine, which is the only COVID-19 vaccine currently approved for any pediatric population in the U.S. Experts have said that the availability of a non-mRNA vaccine could help reduce COVID-19 vaccine hesitancy.
The trial enrolled 2,247 adolescents aged 12 to 17 years and assigned two-thirds of them to receive two injections of 5 g of vaccine plus 50 g of an adjuvant given 21 days apart. The other third received a placebo.
The trial began in April 2021 and concluded in September, with much of the efficacy data being collected when delta was the dominant circulating SARS-CoV-2 variant.
Overall vaccine efficacy was 79.5% against PCR-positive mild, moderate or severe COVID-19 cases occurring 7 days or more after the second dose, Novavax said. Only mild cases were recorded in either arm — six in the vaccine arm and 14 in the placebo arm. Efficacy was consistent between two age groups — 12 to 14 years and 15 to 17 years.
Among the 11 cases for which sequencing was available, all were caused by the delta variant — three in the vaccine arm and eight in the placebo arm. Efficacy against delta was calculated to be 82%.
“We can demonstrate the neutralizing antibodies that we made in adolescents are not inferior to those in adults, and we could claim that they work at the same level as an adult,” Filip Dubovsky, MPH, chief medical officer at Novavax, said during a call with reporters.
Adolescent neutralizing antibody responses using wild-type SARS-CoV-2 were approximately 1.5-fold higher among adolescents compared young adults aged 18 to 25 years, meeting FDA-specified criteria, Dubovsky said. Moreover, data from the trial demonstrated that adolescents’ functional immune responses against variants were 2.4- to 4-fold higher than adults’ responses.
Published data from the company’s large phase 3 trial showed the vaccine was also highly effective in adults.
“What we've shown you over and over again is the consistency of [the] efficacy of our vaccine, whether it be against the prototype strain or the varying strain,” Dubovsky said.
Data from the pediatric trial showed that the vaccine was well tolerated, with the most common adverse reactions being injection site tenderness or pain, headaches, myalgia, fatigue and malaise.
“What we also did was compare this to the results we got in adults, and after this one, they were generally similar with no increase in severity,” Dubovsky said. “The only increase we really saw are some redness and erythema in the arms of the children, and this is likely just because they have thinner arms, and it was easier to spot these reactions.”
He said there was no increase in reactogenicity in 12- to 15-year-old adolescents compared with 15- to 18-year-old adolescents.