Moderna Announces Its Covid-19 Vaccine Is Effective in Adolescents

The company completed a final phase trials in 3,732 adolescents between ages 12 and 17

A nurse gives a 16-year-old a shot of the vaccine at a clinic in Florida.
A nurse gives a 16-year-old a Pfizer-BioNTech shot at a clinic in Florida. Photo by Paul Hennessy/SOPA Images/LightRocket via Getty Images

Moderna announced on Tuesday that its Covid-19 vaccine is safe and effective at preventing Covid-19 in teenagers.

The Phase 2/3 trial included 3,732 participants, two-thirds of whom received two doses of the Moderna vaccine while the others received a placebo. Four participants who did not receive the vaccine developed Covid-19 during the study. No vaccinated patients tested positive for the coronavirus during the study. Moderna says the results are “consistent with a vaccine efficacy of 100 percent,” John Bonifield and Lauren Mascarenhas report for CNN. Using a broader definition for a case of Covid-19, the study showed 93 percent efficacy.

“It’s really great news,” says Yale University immunologist Akiko Iwasaki to the New York TimesEmily Anthes. “These vaccines are working really well in all the age groups and potentially even better in the younger people.”

According to the statement, adolescents had similar side effects as adults who get the Moderna vaccine: headaches, fatigue, muscle pain and chills. (The Moderna vaccine has been authorized for use in adults aged 18 and older since December 18, 2020.) No safety concerns have been identified in adolescents, and most of the side effects were mild or moderate. Moderna notes that it will gather data until 12 months after each participant’s second dose of the vaccine to continue to assess the vaccine’s safety in the long term.

Johns Hopkins University’s Rupali Limaye, who studies vaccine use and hesitancy, tells the Times that the availability of a second vaccine for use in adolescents could give parents and guardians more confidence when deciding whether to vaccinate their kids. But because both Moderna and Pfizer-BioNTech’s vaccines require two doses given several weeks apart, Limaye says it may be difficult to fully vaccinate everyone who wants a vaccine.

“I think we’ll still unfortunately not be able to reach more underserved populations that are facing vaccine disparities, because it’s still the two-dose regimen,” says Limaye to the New York Times.

Moderna says it plans to submit its data for review by the U.S. Food and Drug Administration and other global regulators in early June, and that it will submit the findings for publication in a peer-reviewed journal. The review process could take about a month, based on the timeline for Pfizer-BioNTech’s vaccine, which was authorized for use in adolescents on May 10, per Berkeley Lovelace Jr. at CNBC. So it is possible that the Moderna vaccine could be available for teens by mid-summer, which would allow them to be fully vaccinated by the fall.

“Having adolescents vaccinated against the virus is really going to limit spread in school to a great degree,” says pediatric infectious disease expert Dr. Sean O’Leary, who works at the University of Colorado Anschutz Medical Campus, to the New York Times. “It potentially could even change mask requirements for school, depending on the level of vaccination uptake. I’m looking forward to a much different school year next year, primarily because of vaccination.”

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