FDA commissioner Janet Woodcock on Covid vaccine approval for kids: 'We’ll do that as quickly as we can'

Once submitted, the agency will weigh the benefits against any potential harm or side effects, the same way it would any other pediatric vaccine — but acting FDA commissioner Dr. Janet Woodcock acknowledges the urgency and concern that parents feel.

"We'll do that as quickly as we can," Woodcock said on an episode of the "In the Bubble with Andy Slavitt" podcast on Monday.

Woodcock declined to offer a specific timeline, but other experts weighed in on Monday to provide a realistic projection. Here's what that could look like, and what needs to happen between now and then:

The FDA could take four or six weeks to review Pfizer's application, former FDA head Scott Gottlieb told CNBC on Monday. Assuming the data meets all of the FDA's standards, that means school-aged children could get shots by the end of October or early November, said Gottlieb, a current Pfizer board member.

The estimate is based on how long it took the FDA to approve the vaccine for kids in the older age group, 12 to 15.

Dr. Anthony Fauci, the White House's chief medical advisor, also says this timeframe is likely. "I think there's a really good chance it will be before Halloween," Fauci told MSNBC's Hallie Jackson on Monday.

Of course, all of this depends on the FDA's analysis. If the agency finds any significant safety concerns, for example, it would pause the process to investigate them — extending the timeline much further.  

Children are not simply small adults; their immune systems respond completely differently to vaccinations, which is why children can't get the exact same Covid vaccine as grown-ups.

Vaccines for kids require a "different formulation," Woodcock said. For the Covid vaccine, she said, that means finding a dosage that's appropriate for their developing immune systems. Dosage is typically determined by factors like weight, age and how that particular vaccine moves throughout the body.

A vaccine dose that's too high could cause severe short-term side effects, including worse fevers and headaches than some adults have experienced while getting vaccinated. A dose that's too low may be ineffective.

The FDA is also responsible for reviewing manufacturing and checking for quality control, which could become much more stringent if the vaccines for kids are made at lower concentrations than their adult counterparts.

"We're going to have to look at the manufacturing, if there are lower concentrations, and make sure they're reliable so that you're getting the same product every time," Woodcock said.

The FDA has to look at Pfizer's clinical data to "make sure that children responded to the vaccine the way we would expect, and that the safety profile is acceptable," Woodcock said. "In other words, the benefits of the vaccine to children [need to] exceed the potential harms."

Researchers are particularly looking into the potential risks of myocarditis, or inflammation of the heart, which tends to be more common on adolescents than adults. The condition is a rare side effect of the mRNA vaccines — and fortunately, Woodcock said, most cases reported by recently vaccinated people are not severe. "But we want to make sure that the safety of the vaccine in the younger children is fully understood," she said.

In that light, the timeline's slow-moving nature makes sense: Pediatric vaccines are often approached with a particular amount of care, with agencies like the FDA ruling out any and all safety concerns before doling out vaccines to kids.

Of course, with high cases of Covid among children, the pressure is on to move as quickly as possible.

"But we have to get this right," Woodcock said. "So, we'll work on it."

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