Moderna study finds vaccine highly effective in preventing COVID-19 in adolescents

Moderna on Tuesday announced that the Phase 2/3 study of its COVID-19 vaccine (mRNA-1273) in adolescents has met its primary immunogenicity endpoint, successfully bridging immune responses to the adult vaccination.

Moderna plans to submit the study results to the FDA and regulators globally in early June and request authorization.

In the study, no cases of COVID-19 were observed in participants who had received two doses of the Moderna COVID-19 vaccine using the primary definition. 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 United States. Moderna said it plans to submit these data to regulators globally in early June.

“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 Moderna CEO Stéphane Bancel. “We will submit these results to the U.S. FDA and regulators globally in early June and request authorization. We remain committed to doing our part to help end the COVID-19 pandemic.”

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 swab or saliva sample positive for SARS-CoV-2 by RT-PCR, a vaccine efficacy of 93% after the first dose was observed.

The company noted that 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, the company said.

Moderna said that safety data continues to accrue, and the study continues to be monitored by an independent safety monitoring committee. All participants will be monitored for 12 months after their second injection to assess long-term protection and safety. Consequently, these data are subject to change based on ongoing data collection.

Moderna plans to submit data from the TeenCOVE study to a peer-reviewed publication.