Moderna Reports Positive COVID-19 Vaccine Results in Adolescents


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.

The phase 2/3 study of Moderna’s COVID-19 vaccine in adolescents has met its primary immunogenicity endpoint, with no cases of COVID-19 observed in participants who received 2 doses of the vaccine, according to a press release.

The trial enrolled 3732 adolescent participants ages 12 to less than 18 and randomized them 2:1 to receive either 2 doses of the mRNA vaccine or a placebo. The primary endpoint was noninferior immunogenicity versus the phase 3 adult study comparator group. According to the Moderna’s press release, 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.

Because the incidence rate of COVID-19 is lower in adolescents, investigators also used a secondary case definition based on the CDC definition of COVID-19. This definition requires only 1 symptom and a nasopharyngeal swab or saliva sample positive for SARS-CoV-2, and the researchers found a vaccine efficacy of 93% after the first dose using this definition.

The vaccine, called mRNA-1273, was generally well tolerated with a safety and tolerability profile consistent with the phase 3 COVE study in adults. To date, researchers have identified no significant safety concerns and the majority of adverse events were mild or moderate in severity. The most common solicited local adverse event was injection site pain, and the most common solicited systemic adverse events after the second dose were headache, fatigue, myalgia, and chills.

The safety data is continuing to accrue, and the trial is continuing to be monitored by an independent safety monitoring committee. All participants will be monitored for 1 year after the second injection to assess long-term protection and safety, so the press release noted that data are subject to change.

“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 Chief Executive Officer Stephane Bancel, MBA, in the press release. “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 [news release]. Moderna; May 25, 2021. Accessed May 25, 2021.

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