The latest on the Covid-19 pandemic in the US

After vaccine advisers to the US Food and Drug Administration rejected Pfizer's application to add a booster dose of its Covid-19 vaccine, several members of the committee voiced doubts that it is a good idea to start giving boosters to the entire population.

They especially expressed concern about younger adults and older teens, who may have a higher risk of a rare complication called myocarditis – an inflammation of the heart.

“Recommending a third dose for younger people is not something I would be comfortable with at this point,” said Dr. Melinda Wharton, director of immunization services at the US Centers for Disease Control and Prevention.

The committee is now discussing voting on another question limiting the approval of a booster dose to a more limited group.

Vaccine data published Friday by the US Centers for Disease Control and Prevention shows more than two million Americans have already taken a Covid-19 booster shot and just over half the population is fully vaccinated, 54.4%.

The data shows:

You can see more of the CDC's data here.

The committee is taking a 10-minute break and will reconvene to discuss voting on another question limiting the approval of a booster dose to a more limited group – possibly people 60 or 65 and older, and those at high risk of occupational exposure.

Vaccine advisers to the US Food and Drug Administration rejected Pfizer’s application to add a third, booster dose of its coronavirus vaccine to the two-dose regimen. 

Members of the FDA’s Vaccines and Related Biological Products Advisory Committee rejected the application by a vote of 16 to 2. But they reserved the right to amend the question being asked in a second round of voting.

The voting question: Do the safety and effectiveness data from clinical trial C4591001 support approval of a COMIRNATY booster dose administered at least six months after completion of the primary series for use in individuals 16 years of age and older?

Committee members were preparing to vote on a narrower approval – perhaps one that allowed booster doses for people 60 or 65 or older, or for people at high risk of exposure at work.

“I don’t think a booster dose is going to significantly contribute to controlling the pandemic,” said Dr. Cody Meissner, a professor of pediatrics at Tufts University School of Medicine.

Dr. Sanjay Gupta: No, this is not what we were expecting

Members of the US Food and Drug Administration's Vaccines and Related Biological Products Advisory Committee are now voting but they may modify the question they are voting on and vote again.

They are voting on this question: Do the safety and effectiveness data from clinical trial C4591001 support approval of a COMINARNATY booster dose administered at least six months after completion of the primary series for use in individuals 16 years of age and older?

There will be discussion after the vote.

Vaccine maker Pfizer got some strong pushback Friday in a meeting held to discuss the company’s application to approve booster doses of coronavirus vaccine. 

Vaccine advisers to the US Food and Drug Administration are meeting to discuss Pfizer’s request. The company said it has data showing both that immunity wanes six months or so after people are fully vaccinated with two doses, and also that adding a third, booster dose at six to eight months restores that immunity.

But Dr. Phil Krause, deputy director of the FDA’s Office of Vaccines Research and Review, noted that Pfizer was using data that had not been reviewed by experts.

He pointed to one study being used by Pfizer to support its case. “If you take these numbers and put them together, you get an efficacy of 93.3% in the study,” he added. Yet Pfizer said the data suggested a drop in efficacy to 58%-61%. 

Pfizer Senior Vice President Dr. William Gruber said that analysis included waning of immunity over time. But Krause — who signed an unusual letter in the Lancet earlier this week saying there wasn’t yet enough evidence to justify boosters – said the study did not make that case clearly.

“This points out the complexity of this model and the importance of these data being reviewed,” Krause said.

One of the members of the independent committee was also critical. Dr. Michael Kurilla, an infectious disease specialist at the National Center for Advancing Translational Sciences, noted that the studies relied heavily on measurements of antibodies, without looking at other important aspects of immune response.

“It's a little disappointing that there's been very little reporting of the cellular immune responses and an entire focus on the neutralizing antisera,” Kurilla said. “Which clearly for that population at high risk is absolutely essential, but for the broad population in terms of their protection, which seems to be holding up well over time – (that) should be because of adequate cellular immune responses but we have no indication of that,” Kurilla added.

Vaccine advisers to the US Food and Drug Administration are expected to vote soon on whether many Americans need to start getting booster doses of coronavirus vaccine.

Pfizer received full approval for its vaccine from the FDA, so the request to add a booster dose is a supplement to that approval. The data being presented by Pfizer involves a booster given to its volunteers about six months after they finished their first two doses.

The US Centers for Disease Control and Prevention is urging state and local health officials to wait to administer vaccine booster doses until after the US Food and Drug Administration has OK’d them and the CDC has recommended how to use them.

In a letter sent Thursday and obtained by CNN, the CDC said the Biden administration has been making preparations to begin a Covid-19 booster shot rollout as early as the week of Sept. 20, but “any implementation of booster programs should begin after FDA takes a regulatory action and ACIP and CDC make clinical recommendations for use.”

The FDA’s vaccine advisers are meeting about boosters for Pfizer’s Covid-19 vaccine today, and the CDC’s Advisory Committee on Immunization Practices is scheduled to meet about boosters on Sept. 22-23.

The Pfizer/BioNTech Covid-19 vaccine is already approved by the FDA, and third doses have already been authorized for people who are immunocompromised. 

State health officials told CNN this week there was some confusion about rolling out boosters, but health officials are already preparing to administer them to eligible people as early as next week.

Biden administration officials defended the controversial announcement by the White House in which it said it was preparing to roll out booster Covid-19 shots for most Americans by Sept. 20 – well ahead of any consideration by the US Food and Drug Administration and the US Centers for Disease Control and Prevention – saying they were just trying to plan ahead.

The announcement prompted a flurry of criticism from health experts, including former FDA officials, who have told CNN it was unhelpful and unseemly for the White House to make such an announcement ahead of the regulators who are tasked with such decisions.

Vaccine advisers to the FDA are meeting today to discuss the question of giving booster shots.

“Let me go back to why we made the announcement in August that we did. There were two reasons: transparency and planning,” US Surgeon General Dr. Vivek Murthy told reporters Friday.

Scientific leaders in the administration, Murthy said, “had said publicly that we were following the data closely, and if we saw a signal that indicated to us that protection was starting to wane, and that additional shots may be required, that we would be transparent and open with the public about that. That was one of the reasons we felt it was important to speak up when we saw that signal in the data.” 

Murthy noted that administration officials have always been clear that the plan “would be contingent on the FDA and the CDC’s independent evaluation” and that they will follow that evaluation and the recommendations. 

White House Covid-19 response coordinator Jeff Zients suggested that the decision to announce the plan publicly was made with the hindsight from the previous administration’s handling of vaccine emergency use authorization last year.

“In December, when the vaccines were initially authorized for emergency use, there was not a strong plan in place, and we saw that there was a lag in terms of getting shots in arms. So we want to make sure we're ready, whatever decision the agencies make,” Zients said. 

As CNN’s Elizabeth Cohen has reported, Friday’s scientific back and forth is happening against the backdrop of friction between members of the FDA’s vaccines advisers and the Biden administration. Advisers to the FDA told CNN they're upset that Biden announced a booster program before government scientists reviewed the data.