The Food and Drug Administration granted emergency use authorization Wednesday for a third dose of Pfizer and BioNTech's COVID-19 vaccine to be given to three groups — those 65 and older, those at high risk of developing severe COVID-19 and those at risk of developing "serious complications" due to "frequent institutional or occupational exposure," likely including frontline health care workers and those in prisons. The authorization makes the Biden administration's plan to roll out booster shots this week at least partially possible.
"After considering the totality of the available scientific evidence and the deliberations of our advisory committee of independent, external experts, the FDA amended the EUA for the Pfizer-BioNTech COVID-19 Vaccine to allow for a booster dose in certain populations such as health care workers, teachers and day care staff, grocery workers and those in homeless shelters or prisons, among others," acting FDA Commissioner Janet Woodcock said in a statement.
While the first two doses of the Comirnaty vaccine already have thefor use in people 16 years and older, the regulator said it will now allow third shots for select portions of the American population. However, under federal agreements governing use of the shots, most vaccine providers will still need to wait for a committee of vaccine advisers from the Centers for Disease Control and Prevention to formally recommend the third dose.
That group, the CDC Advisory Committee on Immunization Practices, met Wednesday to discuss the potential use of Pfizer's booster shots. It reviewed safety data collected from the millions of Americans who have already received additional doses of vaccine.
The committee had previously discussed prioritizing booster doses for those at highest risk of severe so-called "breakthrough" infections and essential frontline workers like doctors and nurses, where even outbreaks of mild cases of COVID-19 can sideline fully vaccinated providers and cripple hospitals.
The committee is expected to vote Thursday on its own guidelines for use of the shots.
Pfizer and its German partner BioNTech had initially sought full approval of its booster shot doses in all adults and teenagers at least 16 years old, citing promising data from its own trials and other countries that have administered third doses.
On Wednesday, the CDC presented new data to the ACIP underscoring waning vaccine effectiveness against symptomatic infection in the face of the Delta variant, and potentially against severe COVID-19 among older adults. A CDC scientist also presented modeling suggesting that booster shots could help curb cases in nursing homes, but cautioned that vaccinating seniors alone might only have a "small to moderate" effect on curbing the pandemic's spread overall.
The third dose of Pfizer's vaccine has not presented any safety concerns among those who have so far received one, CDC officials said. Around 2.3 million Americans have received an additional dose since authorities first allowed them for some immunocompromised people.
The agency also released several studies suggesting vaccine effectiveness against infection and hospitalization has declined for many adults, though rates of COVID-19 remain Americans. A CDC investigation into a Delta variant outbreak at a federal prison in Texas was released Tuesday. It underscored the risk of breakthrough infections in crowded settings, with 70% of fully vaccinated inmates testing positive for the virus.
But the FDA's own panel of vaccine advisers voiced concerns over gaps in the data supporting broad need and safety for booster shots in a, and ultimately endorsed a narrower authorization for the shots.
"We're grateful for the advice of the doctors, scientists, and leading vaccine experts on our advisory committee and the important role they have played in ensuring transparent discussions about COVID-19 vaccines," Dr. Peter Marks, the FDA's top vaccines official, said in a statement.
"The FDA considered the committee's input and conducted its own thorough review of the submitted data to reach today's decision," Marks said.
The FDA's decision applies only to people who received both doses of Pfizer's COVID-19 vaccine at least six months ago. The regulator has yet to authorize Moderna or Johnson & Johnson booster shots, though federal health officials have said they expect most Americans will eventually need an additional dose.
Moderna only recently submitted to the FDA data supporting a booster dose of its COVID-19 vaccine. It halved its third dose from 100 micrograms to 50 micrograms. Pfizer's booster shot is the same as the first two doses.
Johnson & Johnsondata from its vaccine trials suggesting the single-shot Janssen vaccine remained mostly effective at preventing severe disease but also that a second dose could boost protection.
Scientists at the National Institutes of Health are also working to release data from trials in which they mix-and-match booster shots. The results are expected to be announced as early as this month.
"We are right in the middle of those trials to see, can you mix and match any one of the three that have emergency use authorization, can you start with one and boost with the others? We're going to know more about that just in the course of the next two or three weeks," NIH Director Francis Collins told "Face the Nation".
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