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A vaccine advisory panel voted Thursday to recommend that a wide swath of Americans should be offered Covid-19 vaccine booster shots, given at least six months after their second vaccination. But a vote that would have ensured access to boosters for health care workers and others in high-risk occupations did not pass, leaving many of them for now out of the eligibility pool.

The recommendations — which pertain at this time only to people who were previously vaccinated with the Pfizer-BioNTech vaccine — now go to Rochelle Walensky, director of the Centers for Disease Control and Prevention. She is not bound to follow recommendations from the Advisory Committee on Immunization Practices but it would be highly unusual for a CDC director to reject the ACIP’s advice.

Walensky is expected to approve the recommendations on Thursday, opening the door for the booster shot program to begin soon, potentially in the week that the Biden administration had set as its target.

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The ACIP voted on a series of questions, each of which cast a broader net in terms of who in this country would be eligible to get a booster shot at this point. The committee agreed unanimously to recommend to boosters for people 65 and older as well as people living in nursing homes.

With each successive vote, however, the committee’s support for recommending boosters ebbed, with increasing numbers of members questioning the strength of the evidence supporting the need. A vote to recommend boosters for people aged 50 to 64 with medical conditions that raise the risk of severe Covid infection passed 13 to 2. A vote to recommend boosters for people aged 18 to 49 with medical problems passed with a 9 to 6 vote.

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But the committee drew the line at a recommendation that would have given access to boosters to people aged 18 to 64 who are at elevated risk because they live in a setting or work in an occupation where the risk of catching Covid-19 is significant. This would include health workers, prisoners and prison guards, and people who live in or work in homeless shelters.

The recommendation was defeated by a 9 to 6 vote.

“We might as well give it to everybody,” Pablo Sánchez, a professor of pediatrics at Ohio State University and committee member, said of the last vote. Sarah Long, a pediatrics professor at Drexel University College of Medicine, called it “a very slippery slope” that seemed “uncharacteristically open-ended” given the lack of data supporting both the benefit and the need. Long voted against all but the first of the four recommendations.

Sánchez said he was concerned offering booster shots so broadly at this point would send the wrong message about how well the Covid vaccines are working. “This is like saying the vaccine isn’t working. And it is working.”

But Helen “Keipp” Talbot, associate professor of medicine at Vanderbilt University, urged colleagues to vote for the recommendation as a way to boost the immunity of health workers. Hospitals are struggling under the crush of Covid patients, she said, and when health workers get sick, there’s no one to step in.

“Having the option to give health care workers a third dose helps us to maintain our staffing,” said Talbot, who voted yes on all four recommendations.

Some outside experts who have been skeptical of offering boosters broadly said they supported ACIP’s vote against including the last group — even though the Food and Drug Administration expressly included them in its explanation of who it felt should be eligible for Covid booster shots in an emergency use authorization issued late Wednesday.

Supporting boosters based on occupation would have in effect opened up the shots to all adults who wanted to go out and get one, said Norman Baylor, a vaccine industry consultant who formerly ran FDA’s vaccines program office.

Baylor noted most Covid vaccines are being administered by pharmacists, a group not equipped to check bona fides beyond age if an individual showed up for a booster saying they worked or lived in one of the named settings. “You might have asked the question, 18 and above, period,” he said.

Paul Offit, a pediatric infectious diseases specialist at Children’s Hospital of Philadelphia, agreed. Offit, who serves on the FDA’s vaccine advisory body, said he was planning on waiting a bit before he gets a third shot — he’s 70 — because as of now, there was not much data about booster shots and that the data showed that two doses were continuing to offer excellent protection against severe disease.

“I’m going to wait to see how this plays out,” Offit said.

The FDA authorization issued Wednesday covers a Pfizer booster shot for those 65 and older and a wide array of people who are at higher risk of severe Covid because of health conditions or because they have “frequent and unavoidable exposure” to the SARS-CoV-2 virus in institutional or occupational settings.

Despite the fact that ACIP voted not to make the final recommendation, many Americans will now find themselves eligible to for a booster shot — if they received the Pfizer and BioNTech vaccine as their primary vaccination series. So far only Pfizer and BioNTech have secured FDA authorization for a booster shot. Nearly 100 million people in the United States have received two doses of the Pfizer vaccine. The third shots should be given sometime after six months have elapsed from receipt of the second dose.

The decision to begin to offer booster shots to a large number of Americans flies in the face of a call by the World Health Organization for countries to place a moratorium on giving boosters until the end of the year in a bid to try to make more doses available to low- and middle-income countries that have struggled to get access to vaccine.

Ruth Faden, a medical ethicist at Johns Hopkins Berman Institute of Bioethics, expressed some disappointment in the U.S. move to offer boosters now, though she said the ACIP’s rejection of the final recommendation limited some of the impact the effort will have on global supplies.

“Did the United States strike the balance this time on this booster decision? It could have been worse, it could have been better. It certainly could have been better,” she told STAT.

A number of ACIP members were clearly unhappy they could not recommend the Pfizer booster be made available to all people who fall into the groups that qualify for a booster shot, regardless of their initial doses. But the FDA said it did not have evidence on which to recommend that people who got Moderna’s two-dose vaccine or the one-dose Johnson and Johnson vaccine should get a Pfizer jab as their third or second shot respectively.

Peter Marks, director of FDA’s vaccines division, told the committee FDA understands the frustration about not being able to give boosters at this point to people who did not get the Pfizer vaccine. The agency is working with manufacturers and will try to fill this gap as quickly as possible, he said.

While most members of the committee supported the use of boosters, several raised concerns that this step won’t fix the country’s Covid problem. Talbot said hospitals are full of people with Covid-19 who aren’t vaccinated. Boosting fully vaccinated people won’t change that.

“I feel like we’re putting lipstick on frogs,” she said. “This is not going to solve the pandemic.”

Thursday’s ACIP vote caps a rocky five-week period in which the Biden administration found itself at odds with many in the scientific community — and those who value drug and vaccine approvals playing out according to regulatory pathways.

Rather than asking the FDA and the CDC to advise it on whether it was time to make booster shots available to Americans, the administration announced a booster shot campaign would begin the week of Sept. 20. The announcement was made before any booster shots had been authorized for use — and before two of the three manufacturers had even filed an application to the FDA for approval of a booster.

Whether most fully vaccinated people need a booster shot at this point remains a point of heated debate. While data from Israel — one of the first countries to rapidly vaccinate a large portion of its population — suggests the Pfizer vaccine’s ability to protect against serious disease subsides within months, many questions remain about the interpretation of those data. And as Israel only used the Pfizer vaccine, the country’s experience tells the world nothing about other vaccines in use.

The FDA’s vaccine advisory committee, the Vaccines and Related Biological Products Advisory Committee, or VRBPAC for short, voted at a meeting last Friday not to recommend boosters for everyone 16 years of age and older who had received the Pfizer vaccine. Instead, it recommended a smaller group of individuals be offered boosters — people 65 and older and people at high risk of severe disease.

Pfizer had applied for approval of a booster that would be offered to anyone aged 16 and older, to be given six months after the second dose of vaccine. But Pfizer’s application included no data to support the safety of giving 16- and 17-year olds a booster and members of VRBPAC objected strongly to their inclusion without safety data. In the end, the FDA did not include them.

Andrew Joseph contributed reporting. 

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