Scientific advisors from the Centers for Disease Control and Prevention faced a delicate challenge on Thursday: Who qualifies for the new Pfizer BioNTech coronavirus booster and why?
On Wednesday evening, the Food and Drug Administration approved a booster of the vaccine for people over 65 who had received their second at least six months earlier. The agency also approved boosters for adult Pfizer BioNTech recipients who are at high risk of severe Covid-19 or who are at serious work complications from exposure to the virus.
About 22 million Americans have had their second dose of Pfizer at least six months, according to the CDC, and about half are 65 years of age or older.
But who exactly is at risk of becoming seriously ill? What does it mean to be exposed in the job? Do teachers count as exposed or just frontline healthcare workers? And what about Americans who got the Moderna and Johnson & Johnson recordings?
These are questions that scientists on the CDC Advisory Committee on Vaccination Practices have discussed, and their decisions will shape the guidelines of the federal government.
In its deliberations on Wednesday, the CDC Advisory Committee answered open questions.
A third dose will undoubtedly increase antibody levels, the experts concluded. However, it is so far unclear how long this increase will last, whether it represents a useful additional protection against serious diseases and whether it can significantly reduce the transmission of the virus.
Scientists on the committee also noted the lack of safety data, especially among younger people. And several consultants said the goal of the boosters should be to prevent serious illness, hospitalizations, and death, rather than fighting off infection.
“I don’t think there is any hope that vaccines like the one we have will prevent infection after the first, maybe a few weeks, that you have these extraordinary immediate reactions,” said Dr. Sarah Long, pediatric infectious disease expert at Drexel University College of Medicine in Philadelphia.
The advisors also struggled with the practicalities of advocating a booster of Pfizer’s vaccine, but not Moderna or Johnson & Johnson. Recipients of these vaccines may hear that a booster dose is needed – but they may not be able to get it yet.
“This is a major public health panic that we want to avoid,” said Dr. Long.
Moderna has applied for FDA approval for booster syringes, but at half the dose stated in the first two.
Mixing the first few shots of the Moderna vaccine with a Pfizer booster – or vice versa – is untested territory, and federal agencies are always reluctant to take steps that the evidence doesn’t specifically support.
Some global health experts have criticized the Biden government for pushing booster injections even though much of the world has not yet received a first dose. But on Wednesday, the White House press secretary Jen Psaki argued that it was a “wrong decision.”
On Wednesday morning, President Biden said the United States would buy 500 million more doses of the Pfizer BioNTech vaccine to donate worldwide, with purchases doubling in July.
“We are now donating three shots worldwide for every shot we give an American, and we continue to believe we can do both,” said Ms. Psaki. “Our view remains that frankly the rest of the world needs to do and do more.”
Sharon LaFraniere and Noah Weiland Reporting from Washington contributed. Daniel E. Slotnik Reporting from New York contributed.