Besides updating the authorization for the Pfizer COVID-19 vaccine, the agency also shortened the recommended time between a second dose and the booster to 5 months or more, based on new evidence. In addition, a third primary series dose is now authorized for certain immunocompromised children 5 years to 11 years old. Full details are available in an FDA news release.
The amended emergency use authorization (EUA) only applies to the Pfizer vaccine, said acting FDA Commissioner Janet Woodcock, MD.
“Just to make sure every everyone is clear on this, right now: If you got [Johnson & Johnson’s one-dose vaccine], you get a booster after 2 months. If you got Moderna, you can get a booster at 6 months or beyond,” she said during a media briefing.
What is new, she said, is “if you got Pfizer as your primary series, you can get a booster at 5 months or beyond.”
A lower risk of myocarditis?
Asked about concerns about the risk of myocarditis with vaccination in the 12- to 15-year age group, Dr. Woodcock said they expect it would be “extremely rare with the third dose.”
“We have the real-world evidence from the Israeli experience to help us with that analysis,” she said.
The data so far consistently points to a higher risk of myocarditis after a second mRNA vaccine dose among males, from teenagers to 30-year-olds, with a peak at about 16 to 17 years of age, Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, said during the media call.
The risk of myocarditis is about 2 to 3 times higher after a second vaccine dose, compared to a booster shot, Dr. Marks said, based on available data. It may be related to the closer dose timing of the second dose versus a third, he added.
“The inference here is that on the risk of myocarditis with third doses in the 12- to 15-year age range is likely to be quite acceptable,” he said.
Dr. Marks also pointed out that most cases of myocarditis clear up quickly.
“We’re not seeing long-lasting effects. That’s not to say that we don’t care about this and that it’s not important,” he said.
“But what it is saying is that in the setting of a tremendous number of Omicron and Delta cases in this country, the potential benefits of getting vaccinated in this age group outweigh that risk,” Dr. Marks said. “We can look at that risk-benefit and still feel comfortable.”
He said that “the really overwhelming majority of these cases, 98%, have been mild” -- shown by a 1-day median hospital stay.
Even so, the FDA plans to continue monitoring for the risk of myocarditis “very closely,” he said.
Interestingly, swollen underarm lymph nodes were seen more frequently after the booster dose than after the second dose of a two-dose primary series, the FDA said.
Reducing the time between primary vaccination with the Pfizer vaccine -- two initial doses -- and the booster shot from 6 months to 5 months is based on decreasing efficacy data that the drugmaker submitted to the FDA.
The 5-month interval was evaluated in a study from Israel published Dec. 21 in the New England Journal of Medicine .