But have A second available vaccine might not result in a large vaccination surge, at least in the 6-11 year old age group, where demand has been weak. Only 29 percent of the children in this group received the two-shot regimen of Pfizer’s BioNTech vaccine, according to the CDC.
Increasing uptake “really takes a lot of one-on-one conversations and educating providers and parents about the benefits,” said Amanda Cohn, chief medical officer of the CDC’s National Center for Immunization and Respiratory Diseases and a member of the advisory committee.
Despite the unanimous support for the vaccine, some of the advisers expressed concerns that the data on the vaccine was limited and outdated as the studies were conducted before the Omicron variant of the coronavirus emerged. They said the vaccine would likely be beneficial in preventing serious illnesses but not as helpful in blocking mild infections.
“We’ve crossed a line,” said Paul A. Offit, a professor of pediatrics at the Children’s Hospital of Philadelphia, as the highly transmissible Omicron and its subvariants, which require a third dose for protection, arrived. He said he supports approval — as long as a third Moderna dose is on the way.
“We are in a different phase of this pandemic,” Offit said. “I think the benefits clearly outweigh the risks, but I say that with due comfort there will be a third dose.” Children who receive a two-dose series should not be considered “fully vaccinated,” he said .
Moderna told advisers it’s testing a booster shot for ages 6 to 17 and will seek FDA approval in the coming months — perhaps by July.
Tuesday’s meeting ushered in one of the busiest weeks in vaccine policy since the pandemic began. On Wednesday, the agency’s external experts, the Vaccines and Related Biological Products Advisory Committee, are scheduled to discuss whether Moderna and Pfizer-BioNTech vaccines should be used for the youngest children. For the Pfizer BioNTech vaccine, this includes babies and children aged 6 months to 4 years. And for Moderna, it’s children aged 6 months to 5 years.
If the FDA and CDC give their blessings later this week, the vaccines will be available starting next week, Biden administration officials said. Babies and young children are the only group who do not have access to a vaccine.
However, Tuesday’s action focused on the use of the Moderna vaccine in children aged 6 to 17. The consultants considered two groups: 6 to 11 years old and 12 to 17 years old. Both votes for approval were 22 to 0.
Last week, FDA scientists said the shot was safe and effective for all pediatric ages. According to the staff report, Moderna’s safety, immune response, and efficacy data showed “a favorable risk-benefit profile.”
Some parents have questioned the need for child vaccinations now given the relatively low risk Covid-19 poses to young people.
But Katherine E. Fleming-Dutra, a physician with the division of coronavirus vaccine policy at the CDC’s National Center for Immunization and Respiratory Disease, said it’s impossible to predict which children will develop serious illness.
“Certainly children with underlying medical conditions are more at risk, but half of children aged 6 months to 4 years hospitalized with Covid-19 have no underlying medical conditions,” she said.
Moderna said in a presentation that for every 1 million doses of vaccine distributed in the United States, 95 hospitalizations and 24 ICU stays would be avoided for children ages 6 to 11. For children aged 12 to 17, 200 hospitalizations and 52 intensive care unit stays would be avoided, the company estimates.
Clinical trials have shown that the Moderna vaccine elicits an immune response — virus-blocking antibodies — that is at least as strong as the protection afforded to vaccinated young adults, the agency’s main measure of effectiveness. The vaccine has no side effects, the FDA said.
The primary purpose of testing the pediatric coronavirus vaccines is not to directly measure whether the vaccinations have prevented symptomatic illness. Instead, following a regulatory approach often used to extend vaccine eligibility to younger age groups, the scientists measured levels of virus-blocking antibodies in the blood of children and compared those measurements to levels that are protective in young adults.
But the agency said the trials also provided limited “supportive evidence” for the vaccine’s effectiveness and the impact of variants of the coronavirus on the vaccine.
The studies showed that based on how many children in the vaccine groups versus placebo groups developed Covid, efficacy was 93 percent in children aged 12 to 17 tested when the original strain and alpha variant were dominant . The rate was 77 percent for children between the ages of 6 and 11, when the delta variant caused the most infections. Efficacy dropped to 51 percent and less in children under 6 years tested during the Omicron-induced surge, also weakening the efficacy of the gap in adults. Overall, the number of Covid cases was low.
The Moderna shots are administered 28 days apart. Children aged 6 to 11 years receive 50 micrograms per injection, half the adult dose. Adolescents receive the adult dose. The third, or booster, dose for both groups is 50 micrograms, the company said.
Moderna applied for permission to use its vaccine in adolescents more than a year ago, but the approval was held back over concerns about the risk of rare cardiac side effects — inflammation of the heart muscle and surrounding tissues — called myocarditis and pericarditis. Both the Moderna and Pfizer-BioNTech vaccines have been linked to heart problems in young adult men. Most cases are mild, and inflammation caused by Covid tends to be more severe.
There were no confirmed cases of myocarditis or pericarditis in the Moderna studies of infants, children, and adolescents — but the studies may have been too small to include them. FDA officials said the benefit-risk balance is favorable, but the vaccine’s safety and effectiveness will be closely monitored when it goes to market and is used more widely.
The advisors raised questions about how long the Moderna vaccine would provide immune protection against the coronavirus and whether it would be effective against the Omicron subvariants circulating in the United States.
“Early on in the pandemic, it was pretty clear that the bar was a little lower in terms of vaccine effectiveness because we were trying to get vaccines to market and protect the population,” said Wayne Marasco, a professor of medicine at the Harvard Medical School and the Dana-Farber Cancer Institute. But Marasco said he hopes companies will develop vaccines that have a better shelf life and offer protection against infection that lasts longer than a few months.