The Food and Drug Administration took action Friday to allow school-age children to qualify for COVID-19 vaccines as soon as next week.

The FDA authorized a two-dose series of the Pfizer-BioNTech vaccine, but with just one-third of the active ingredient, for children 5 to 11 years old. The two shots are to be administered three weeks apart, just like in adults.

“The FDA is committed to making decisions that are guided by science that the public and healthcare community can trust. We are confident in the safety, effectiveness and manufacturing data behind this authorization,” said top vaccine reviewer Peter Marks, who is also director of the FDA’s Center for Biologics Evaluation and Research, in a statement.

Thousands of children this age have gotten sick enough from COVID-19 to land in the hospital or intensive care unit, and at least 146 have died nationwide since the pandemic began. It is among the top 10 causes of death of children in this age range. A particular concern for the 5 to 11 age range is multisystem inflammatory syndrome in children, or MIS-C, which can occur alongside COVID-19 in children.

This fall, a return to classrooms and the delta variant led to the largest surge in this age group since the pandemic began.

The FDA has been independently verifying the data supporting the safety and efficacy of the kid-sized doses, in addition to data showing they are necessary, since Oct. 6. Last week, a group of independent scientific advisers overwhelmingly recommended that the FDA authorize the shots after picking apart the data and asking questions of the FDA, the Centers for Disease Control and Prevention and Pfizer for over eight hours in a public meeting streamed on YouTube.

As part of its number-crunching, the FDA modeled how many COVID-19 cases and cases of heart inflammation known as myocarditis might be expected for every million vaccinated kids in this age range.

No children were expected to die of myocarditis after vaccination, even when the FDA’s statisticians inputted a “significant overestimate” for the number of myocarditis cases. On the other hand, the FDA has projected that for every million pediatric vaccinations, about 17 deaths from COVID-19 among boys younger than 17 would be prevented.

The vaccine is 90.7 percent effective in these children. The immune systems of children rev up just as strongly as the immune systems of teens and young adults, even with the less potent dose, the FDA said. The agency’s independent advisers also expect the less potent dose will lead to fewer side effects.

Twenty-eight million children are expected to be newly eligible for Pfizer’s shot.

FDA oversight

An emergency use authorization is an expedited approval process to make vaccines, therapeutics and tests available in response to a national emergency like a pandemic.

But last year, the FDA acknowledged that the bar needed to be set higher for COVID-19 vaccines, even under the EUA process, and laid out rigorous requirements for the vaccine-makers approaching the requirements under a typical, pre-pandemic approval, including the collection of two months of safety data. The vast majority of side effects from vaccines, even rare ones, occur within a few weeks of vaccination.

Pfizer and the FDA were able to move through the data more quickly than normally because they homed their resources on this urgent question, experts say.

“There’s no difference in the safety standards,” said Emmanuel Walter Jr., a pediatrician and chief medical officer at the Duke Human Vaccine Institute who is not on the advisory committee. “The enrollments are more rapid, getting the data assembled is more rapid, getting the data reviewed is more rapid, and it’s done on an ongoing basis with the FDA. So yes, there’s a sense of rapidity, but it is meeting all the same safety standards.”

“I’d look first at the experience so far with this vaccine and the millions of doses that have been administered to older children and adults, and look at the safety track record there, which has actually been quite good,” he added.

For the pediatric vaccines, Pfizer-BioNTech and the FDA went further, proactively collecting any reports of chest pains in order to detect any warning signs of myocarditis or pericarditis, a rare side effect that can occur in young males. None of the children in Pfizer’s testing experienced myocarditis or pericarditis.

Children age 12 and older who have experienced myocarditis after infection have recovered more quickly than adults, and myocarditis stemming from vaccination is not as severe as myocarditis following a viral infection like COVID-19.

FDA adviser Patrick Moore, distinguished professor of microbiology and molecular genetics at the University of Pittsburgh School of Medicine, highlighted the deaths of the American children who died from COVID-19.

“In contrast, we’re very worried about a side effect that is real and cannot be dismissed,” Moore said. “But, fortunately, no one has died from that.”

Vaccines are likely to begin shipping to states this weekend, according to Claire Hannan, executive director of the Association of Immunization Managers.

Jeff Zients, White House COVID-19 response coordinator, said earlier this week that states have now placed initial orders of vaccines for kids and will be ready to go once the CDC gives the green light.

“Upon FDA authorization of the vaccine, millions of doses will be shipped immediately to tens of thousands of pediatricians, family doctors, children’s hospitals, community health centers, rural health clinics, and pharmacies –– providers parents and kids know and trust,” Zients said.

Anti-vaccine groups have spread misinformation that pediatric vaccines will be mandatory, leading to a deluge of emails received by members of the FDA’s advisory committee in recent days opposing their endorsement. In response, the FDA has stressed ultimately it’s a decision each family is free to make.

Some experts acknowledged that parents may be inclined to “wait and see” for more information before vaccinating their children if the kids have already tested positive for the coronavirus and may have some temporary natural immunity.

Protection against severe infection and death from the vaccine are likely to be long-lasting and protect children as their immune systems mature.

“This virus is going to be with us for a long time. And children grow up,” said Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia.