A Phase 2/3 study of the Moderna COVID-19 vaccine (mRNA-1273) in adolescents age 12-17 met its primary immunogenicity endpoint, successfully bridging immune responses to the adult vaccination, according to the company, which will submit the vaccine for expanded FDA authorization for this age group in June. mRNA-1273 was authorized for emergency use in adults age 18 and older in December 2020.
In the trial, no cases of COVID-19 were observed in participants who had received two doses of the Moderna COVID-19 vaccine using the primary definition, according to the company. In addition, a vaccine efficacy of 93% in seronegative participants was observed starting 14 days after the first dose using the secondary CDC case definition of COVID-19, which tested for milder disease. This study, known as the TeenCOVE study, enrolled more than 3,700 participants ages 12 to less than 18 years in the US.
In this Phase 2/3 study, 3,732 adolescent participants ages 12 to less than 18 years were enrolled and randomized 2:1 to two 100 µg doses of mRNA-1273 or placebo. The primary endpoint of non-inferior immunogenicity versus the Phase 3 adult study comparator group was met. After two doses, no cases of COVID-19 were observed in the vaccine group using the case definition from the adult Phase 3 COVE study, compared to 4 cases in the placebo group, resulting in a vaccine efficacy of 100% starting 14 days after the second dose. Because the incidence rate of COVID-19 is lower in adolescents, a secondary case definition based on the CDC definition of COVID-19 was also evaluated to include cases presenting with milder symptoms. Using the CDC definition, which requires only one COVID-19 symptom and a nasopharyngeal (NP) swab or saliva sample positive for SARS-CoV-2 by RT-PCR, a vaccine efficacy of 93% after the first dose was observed.
mRNA-1273 was generally well tolerated with a safety and tolerability profile generally consistent with the Phase 3 COVE study in adults. No significant safety concerns have been identified to date. The majority of adverse events were mild or moderate in severity. The most common solicited local adverse event was injection site pain. The most common solicited systemic adverse events after the second dose of mRNA-1273 were headache, fatigue, myalgia and chills.
“We are encouraged that mRNA-1273 was highly effective at preventing COVID-19 in adolescents. It is particularly exciting to see that the Moderna COVID-19 vaccine can prevent SARS-CoV-2 infection,” said Stéphane Bancel, Chief Executive Officer of Moderna. “We will submit these results to the US FDA and regulators globally in early June and request authorization. We remain committed to doing our part to help end the COVID-19 pandemic.”