Moderna COVID-19 Vaccine Safe, Effective in Adolescents

The TeenCOVE study ( NCT04649151) included over 3700 US adolescents aged 12 to less than 18 years.

Immune responses in adolescents administered the Moderna COVID-19 Vaccine (mRNA-1273) were found to be noninferior to those of an adult comparator group in the phase 2/3 TeenCOVE study.

The TeenCOVE study ( NCT04649151) included over 3700 US adolescents aged 12 to less than 18 years. Patients were randomly assigned 2:1 to receive two 100µg doses of the Moderna COVID-19 Vaccine 28 days apart or placebo. The primary endpoint was noninferior immunogenicity based on a comparison of the geometric mean of the serum neutralizing antibody level in the adult phase 3 COVE study ( NCT04470427).

Results showed that the trial met its primary immunogenicity endpoint. Vaccine efficacy was observed to be 100% starting 14 days after the second dose; no cases of COVID-19 were reported in the vaccine group compared with 4 cases in the placebo group. As the incidence of COVID-19 is lower in adolescents, the study also included a secondary case definition that included cases presenting with milder symptoms. Using this definition (1 COVID-19 symptom and a positive SARS-CoV-2 RT-PCR test), vaccine efficacy was reported to be 93% in seronegative participants starting 14 days after the first dose.

The most common adverse reactions observed after the second dose of the vaccine were headache, fatigue, myalgia and chills. According to the Company, participants will be monitored for 12 months after their second dose to assess long-term protection and safety; to date, no significant safety concerns have been identified.

“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.”


Moderna announces TeenCOVE study of its COVID-19 vaccine in adolescents meets primary endpoint and plans to submit data to regulators in early June. [press release]. Cambridge, MA: Moderna, Inc.; May 25, 2021.