Moderna COVID-19 Vaccine Found Safe, 100% Effective in Adolescents Aged 12-17 Years

Grace Halsey

In the phase 2/3 TeenCOVE study, Moderna's mRNA-1273 demonstrated immunogenicity noninferior to that seen in the phase 3 adult study comparator group.

Moderna announced today that its mRNA-1273 vaccine was found to be safe and 100% effective against infection with the SARS-CoV-2 virus among more than 3700 adolescents aged 12 to 17 years who had received 2 doses.

The study met its primary endpoint of non-inferior immunogenicity vs the adult comparator group from the phase 3 COVE study.

The company also reports vaccine efficacy of 93% in seronegative participants starting 14 days after the first mRNA-1273 dose using a secondary CDC case definition of COVID-19 that tested for milder disease.

“We will submit these results to the U.S. FDA and regulators globally in early June and request authorization,” said Stéphane Bancel, Chief Executive Officer of Moderna in a statement. “We remain committed to doing our part to help end the COVID-19 pandemic.”

The phase 2/3 TeenCOVE study included 3732 adolescents aged 12 to <18 years; participants were randomized 2:1 to 2 100 µg doses of mRNA-1273 or placebo.

After 2 doses, there were no cases of COVID-19 observed in the vaccine group using the case definition from the adult phase 3 COVE study, vs 4 cases in the placebo group, for a vaccine efficacy of 100% starting 14 days after the second dose.

To account for the fact that the incidence 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 1 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.

There were no safety concerns and the tolerability profile of mRNA-1273 was generally consistent with the phase 3 COVE study in adults. Adverse events were mild or moderate with pain at the injection site the most common local event and headache, fatigue, myalgia, and chills the most frequent systemic adverse events after the second vaccine dose.

Collection of safety data will continue as will study monitoring by an independent safety monitoring committee. Participants will be followed for 12 months after receiving their second injection to assess long-term protection and safety. Thus, current data are subject to change based on ongoing data collection.

The US FDA granted emergency use authorization of the Moderna CVOID-19 vaccine in individuals aged ≥18 years on December 18, 2020.

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