FDA authorizes COVID vaccines for kids under 5 years old

The FDA authorized COVID-19 vaccines for children as young as 6 months old on Friday, clearing a key hurdle in expanding eligibility for the shots to 20 million babies, toddlers, and preschoolers. The CDC must still sign off before kids under age 5 can start getting vaccinated, which could happen within days.

“Those trusted with the care of children can have confidence in the safety and effectiveness of these COVID-19 vaccines and can be assured that the agency was thorough in its evaluation of the data,” FDA Commissioner Dr. Robert Califf said in a statement announcing the move.

The FDA’s decision comes after unanimous votes of support out of a daylong meeting Wednesday of the regulator’s outside advisers, the Vaccines and Related Biological Products Advisory Committee, which weighed submissions from Moderna as well as Pfizer and its partner BioNTech.

The FDA’s emergency use authorization is enough for shipments to begin around the country to facilities and health care providers who pre-ordered doses for the initial wave of shots. Those are expected to be delivered through the Juneteenth holiday weekend.

However, as with older age groups, federal supply agreements require vaccinators to wait for the CDC’s sign-off before administering shots formulated for younger children.

A panel of the CDC’s own advisers, the Advisory Committee on Immunization Practices, is scheduled to vote on Saturday. Once the CDC director formally greenlights vaccinations following the meeting, federal officials have said they expect many kids can start getting shots as soon as Tuesday, June 21.

Federal officials say most jurisdictions — except for Florida — have pre-ordered doses out of the 10 million total shots that were made available; 2.5 million orders were received for Pfizer’s shots and 1.3 million for Moderna’s.

Providers in the initial wave have ordered only one of the brands in some jurisdictions, though the Biden administration hopes that will even out as supply climbs around the country over future rounds of shipments.

The FDA also moved Friday to authorize Moderna’s vaccine for children 6 through 17 years old, after the company’s request to vaccinate these children had been stalled for months over concerns it might pose a larger risk of heart inflammation side effects in adolescents.

If recommended by the CDC, Moderna’s vaccine would offer the first alternative to the Pfizer shots that have been available in these older children for several months. However, the CDC’s advisers are not scheduled to vote on Moderna’s vaccine for adolescents this weekend.

Smaller vaccine doses for kids — and the differences between Moderna and Pfizer

Unlike the largely similar regimens of the first round of COVID-19 shots that were available in adults, the makers of the two mRNA vaccines have taken different approaches to immunize young kids.

For children ages 6 months to 5 years old, Moderna plans to offer two shots spaced one month apart. Their doses will be 25 micrograms, a fraction of the 100-microgram primary series rolled out last year for adults.

Pfizer and BioNTech’s vaccine will come in a total of three shots administered over the course of 11 weeks, for children ages 6 months through 4 years old. Those doses are sized at 3 micrograms, just one-tenth of the 30-microgram shots for those 12 and older.

Based on studying antibodies against the virus in blood drawn from children during the clinical trials, both combos were strong enough to clear the FDA’s benchmarks for authorization.

Those goal posts are based on comparing their immune response to older children and adults after they had received their first two shots. Some of the children under 5 years old did not clear this threshold after receiving only two of their doses in Pfizer’s trials, the company disclosed to investors last year, so a third dose was required.

“If you want to put your child back in daycare or lower school in September, you have to take the Moderna vaccine. You cannot do it on Pfizer’s schedule. And we know that two doses does not protect, from Pfizer,” Moderna’s CEO Stéphane Bancel said last week at the Jefferies Healthcare Conference.

The FDA’s review noted that Pfizer’s smaller dose likely resulted in the lower side effects seen in the group compared to older ages.

“We already know that, in older individuals, 30% of children are getting the vaccine. There could be a lot of reasons for that, but one of them is the reactogenicity,” William Gruber, Pfizer’s head of vaccine clinical research and development, told the FDA’s advisers, referring to short-term side effects like aches, fever and pain at the injection site.

Moderna’s two doses also resulted in fewer of most types of side effects compared to older age groups in their trial, the FDA’s review noted. Rates of fever were higher in younger kids compared to adolescents and adults for Moderna, though still around levels seen in this age group after other routine vaccines.

Pfizer’s estimate for vaccine efficacy of three doses in fending off symptomatic infection is also much higher than Moderna’s estimate for two doses during the Omicron wave.

But the FDA’s review cited a wide array of limitations on Pfizer’s estimate that were not voiced for Moderna’s, given the few overall cases that have been recorded in Pfizer’s trial so far and the wide ranging dosing intervals. Some trial participants received their third Pfizer shots as late as eight months after their second, the FDA noted.

“I’m also concerned about people comparing the [vaccine effectiveness] estimates or point estimates between these two, which I think is a real problem given the few number of cases,” the CDC’s Dr. Amanda Cohn told the FDA’s committee.

“I believe the vaccine is effective. I do not have any idea what that number will actually end up being,” Cohn said.

Younger children are generally at lower risk of severe COVID-19 compared to their older peers and adults, and many asymptomatic cases have likely gone unreported. No severe cases of the disease were recorded in Moderna’s trial, even among children who had gotten a placebo.

However, officials and experts warned the committee that the virus has still inflicted an unprecedented toll on children. During the Omicron wave, hospitalizations and deaths in young kids surged despite data suggesting most children already had some antibodies from a prior infection.

“We have to be careful that we don’t become numb to the number of pediatric deaths because of the overwhelming number of older deaths here. Every life is important. And vaccine-preventable deaths are ones that we would like to try to do something about,” Marks said on Wednesday, as the committee kicked off deliberations.