Don’t Use Pfizer’s COVID Vax Off-Label in Kids, Experts Warn

Pediatric infectious disease experts are warning that Pfizer’s COVID-19 vaccine, now fully approved and marketed as Comirnaty, should not be used off-label in children under 12.

While full approval gives physicians the legal grounds to administer the vaccine off-label, experts noted that the doses being studied in younger children are much lower than those used in adults. There also have been no data published about use of the vaccine in children under 12.

David Kimberlin, MD, a pediatric infectious disease expert at the University of Alabama at Birmingham, told MedPage Today that the dose authorized for individuals 12 and up is 30 mcg — but the dose being evaluated in kids ages 5 to 11 “is a third of that,” at 10 mcg.

For kids under 5, the dose being studied is only 3 mcg.

“We can’t have physicians writing for the approved 30 mcg dose to be used in someone under 12,” Kimberlin said. “It’s a much higher dose than what’s being studied.”

The lower dose “was chosen because of immunogenicity and reactogenicity,” he added. “We are going to have to get the word out that we should not be simply taking the Pfizer vaccine approved for adults and putting it in the arms of those under 12.”

FDA Acting Commissioner Janet Woodcock, MD, warned against off-label use of the Pfizer vaccine in younger children during a press briefing Monday, warning that they’re “not just small adults.”

“We do not have data on proper dose, nor do we have full data on safety in children younger than what is in the EUA [emergency use authorization], so that would be a great concern that people would vaccinate children,” Woodcock said. “So we believe we need to get the … data on usage in younger children. They are not just small adults; we have learned that time and time again.”

The American Academy of Pediatrics (AAP) also issued a statement warning against off-label use in kids under 12.

“The clinical trials for the COVID-19 vaccine in children ages 11 years old and younger are underway, and we need to see the data from those studies before we give this vaccine to younger children,” AAP President Lee Savio Beers, MD, said in the statement.

AAP expressly warned about not trying to administer lower doses in children.

“We do not want individual physicians to be calculating doses and dosing schedules one-by-one for younger children based on the experience with the vaccine in older patients,” Yvonne Maldonado, MD, chair of AAP’s committee on infectious diseases, said in the statement. “We should do this based on all of the evidence for each age group, and for that we need the trials to be completed.”

“I know parents are anxious to protect their children, but we want to make sure children have the full benefit of ongoing clinical trials,” Maldonado added.

The Pfizer vaccine is still governed by an EUA for kids ages 12-15; it is only fully approved for those ages 16 and up. AAP strongly recommends vaccination in 12- to 15-year-olds, especially as pediatric cases continue to rise due to the more transmissible Delta variant.

AAP reported 180,000 new cases of COVID-19 among children and adolescents for the week ending August 19, a figure on par with rates from mid-December 2020.

Beers said in the statement that vaccinating all those who are eligible now is critical to protecting the youngest children: “That will help reduce the spread of the virus and protect those who are too young to be vaccinated.”

Last month, Pfizer told MedPage Today that it anticipated a readout for the trial in kids ages 5 to 11 “sometime in September,” with data on kids ages 2 to 5 “soon after that,” followed by a safety and immunogenicity readout in kids ages 6 months to under 2 years “sometime in October/November.”

That would be followed by “a potential submission to the U.S. FDA for an EUA once agreed upon with regulators shortly thereafter.”

However, the FDA subsequently asked both Pfizer and Moderna to expand the size of their clinical trials for kids ages 5 to 11, as a “precautionary measure designed to detect rare side effects,” including myocarditis and pericarditis, according to the New York Times.

The Times reported that FDA asked both companies to include 3,000 children in the 5-to-11-year-old group, and one anonymous source described that as double the original number of study participants.

Deputy Managing Editor Molly Walker contributed to this report.