A committee of independent vaccine experts recommended that the FDA grant an emergency use authorization (EUA) for the two-dose Moderna COVID-19 vaccine for kids ages 6 to 17 years.
The Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted 22-0, agreeing unanimously that the benefits of vaccination outweigh the risks in two age groups: kids ages 6 to 11 years and teens ages 12 to 17. They recommended two 50-mcg doses for the younger kids and two 100-mcg doses for teens.
The Pfizer/BioNTech vaccine is already authorized for kids and teens ages 5 to 15 years (and approved in those 16 and up), but FDA authorization of the Moderna vaccine would give this group an additional option. Roughly 18 million kids ages 5 to 11 remain unvaccinated in the U.S., compared with 8.5 million youths ages 12 to 17, presenters at the VRBPAC meeting noted.
"I believe that this will provide families an important option," said panelist Ofer Levy, MD, PhD, of Boston Children's Hospital, noting that it is clear that the benefits of vaccination outweigh the risks, and it is critical to give families who live in high-risk areas or who have kids with comorbidities an additional choice.
Some experts were concerned about whether two doses of the Moderna vaccine will be sufficient to protect kids against the more transmissible, immune-evasive Omicron strain and its subvariants.
"We are at a different point in this pandemic," said Paul Offit, MD, of the Children's Hospital of Philadelphia. The clinical trial data presented showed vaccine efficacy in teens and kids during the Alpha and Delta surges, and it's highly unlikely that a two-dose regimen would protect to the same degree against Omicron, he noted.
"I'm comfortable saying that I think the benefits outweigh the risks, but I say that with the comfort being provided that there will be a third dose," Offit said. "I think if this was not true, I wouldn't feel the same way."
However, Eric Rubin, MD, PhD, of Brigham and Women's Hospital in Boston, said that because it takes a while to produce data, regulators will always be looking at the previous variant to make decisions.
"We are always going to be behind the 8-ball," he said. "We have to make decisions based on the best quality data we have, which is always going to be old data in an outbreak that's constantly moving."
A few members also highlighted the need to continue monitoring cases of myocarditis. Mark Sawyer, MD, of the University of California San Diego, said he was "sobered" by the data on myocarditis. "That clearly needs to be watched closely going forward as we expand the use of the vaccine," he noted.
Among the 54 million doses of the Pfizer/BioNTech vaccine administered to kids ages 5 to 17, the CDC has confirmed 635 cases of myocarditis, said Tom Shimabukuro, MD, MPH, a vaccine safety official at the CDC, who presented data to the advisory committee. Myocarditis cases were rare, he said, and were mainly concentrated among adolescent males.
FDA briefing documents included safety and efficacy data from two ongoing phase II/III clinical trials (studies mRNA-1273-P203 and -P204) that evaluated the Moderna vaccine in teens ages 12 to 17 and kids ages 6 to 11, respectively.
The trial evaluating the vaccine in teens included approximately 2,500 participants who received the vaccine and 1,200 who received a placebo, and the study in younger kids included roughly 3,000 participants who received the vaccine and 995 who received a placebo.
The vaccine met immunobridging success criteria among younger kids and teens, the FDA experts said. Neutralizing antibody geometric mean titers and seroresponse rates among both age groups were noninferior to those in young adults ages 18 to 25.
Among participants ages 12 to 17, vaccine efficacy was 93.3% (95% CI 47.9-99.9) during a time when the ancestral and Alpha strains were predominant, while vaccine efficacy was 76.8% (95% CI -37.3 to 96.6) among kids ages 6 to 11 during a period when Delta was most prevalent.
Adverse events (AEs) were mild to moderate in severity, and were more frequently reported after the second vaccine dose. The most commonly reported AEs were pain at the injection site, fatigue, and headache. Unsolicited AEs were mainly attributable to lymphadenopathy and hypersensitivity reactions.
A review of serious AEs did not raise any safety signals, and there were no confirmed cases of myocarditis and pericarditis reported in the trials, FDA staff said.
Offit urged members of the panel with influence at the CDC to encourage messaging around the necessity of a booster shot in the future.
"Please make sure that this two-dose series is not described as being fully vaccinated, and that the third dose is simply described as being up-to-date or a booster," Offit said. "That's my plea."