FDA Panel Overwhelmingly Backs Emergency Authorization for Pfizer COVID Vaccine

Kerry Dooley Young

December 10, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Federal advisers on Thursday told US regulators that the benefits of Pfizer's COVID vaccine outweigh its risks for people aged 16 years and older, moving this product closer to a special emergency clearance.

The US Food and Drug Administration (FDA) put Pfizer's application before its Vaccines and Related Biological Products Advisory Committee (VRBPAC), seeking expert feedback on what is likely to be the first COVID-19 vaccine cleared for use in the United States.

New York-based Pfizer is seeking an emergency use authorization (EUA) for its vaccine, known as BNT162b2, which it developed with Germany's BioNTech. The FDA asked its advisers to vote on a single question regarding this product: "Based on the totality of scientific evidence available, do the benefits of the Pfizer-BioNTech COVID-19 Vaccine outweigh its risks for use in individuals 16 years of age and older?"

The members of VRBPAC voted 17-4 in favor of the Pfizer vaccine, with one panelist abstaining. The FDA considers the recommendations of its panels, but is not bound by them. The agency is expected to quickly grant the special clearance to Pfizer's vaccine, with the company then expected to complete work needed for a more complete biologics license application (BLA).

The FDA often allows members of its advisory committees to explain the reasons for their decisions to vote for or against an application after the tallies are publicly counted.

But the FDA did not give VRBPAC members this opportunity on Thursday, leaving the public without detailed insight into their support or objections.

Before the vote, several panelists had asked if the FDA could rephrase the voting question, raising the age for the approved group to perhaps 18 years of age. During the day, panelists also had questioned whether Pfizer's studies give enough information to judge whether the vaccine works against severe cases of COVID. And there was a discussion about how Pfizer could address concerns about the potential for allergic reactions to the vaccine, given the news of two healthcare workers who experienced allergic reactions after having the vaccine but who have since recovered.

In closing the meeting, VRBPAC chairman, Arnold Monto, MD, noted that the panel will on December 17 meet again to offer recommendations on Moderna Inc.'s COVID vaccine.

"I believe most of us are going to be revisiting some of these issues in about a week," he said.

The panelist who abstained was H. Cody Meissner, MD, an expert in pediatric infectious disease from Tufts University. He earlier was among the several panelists who raised questions about the limited data available about the benefit to those ages 16 and 17. Those voting against the application were Michael Kurilla, MD, PhD; Archana Chatterjee, MD, PhD; A. Oveta Fuller, PhD, and David Kim, MD, MA, according to a tally read by the FDA staff after the vote.

Meanwhile, Sheldon Toubman, JD, voted in favor of the application according to the FDA staff's tally. Toubman had been a chief critic among VRBPAC members in reviewing Pfizer's application at the meeting. He'd suggested limiting the EUA to healthcare workers and residents of nursing homes. Members of these two groups are expected to be the first in the US to get Pfizer's vaccine, for which there will be only a limited initial supply. That idea gained no traction.

Toubman also pressed for more evidence that Pfizer's vaccine will work against severe cases of COVID.

The FDA staff on December 8 released a largely positive agency review of Pfizer vaccine. The efficacy of a two-dose administration of the vaccine has been pegged at 95%, with eight COVID-19 cases in the vaccine group and 162 COVID-19 cases in the placebo group. The FDA staff said that the 95% credible interval for the vaccine efficacy was 90.3% to 97.6%.

In that review, the FDA staff said there may be a hint from the results observed to date that the Pfizer vaccine may help ward off severe cases of COVID-19. There were 10 study participants that had severe COVID-19 disease after the first dose: one who received the vaccine and nine who received placebo.

"The total number of severe cases is small, which limits the overall conclusions that can be drawn; however, the case split does suggest protection from severe COVID-19 disease," the FDA staff said.

At the meeting today, Doron Fink, MD, PhD, a lead FDA official on the COVID vaccine review, responded directly to Toubman's concerns. There are many examples of vaccines that protect as well if not better against severe disease as they do against mild to moderate disease, Fink said.

"Protecting against disease of any severity is actually a pretty good predictor of protection against severe disease," Fink said, adding that there's already been a "strong result" shown in terms of the efficacy of Pfizer's vaccine.

Rolling Out

Canadian health regulators on December 9 announced their nation's conditional approval of Pfizer's vaccine for people ages 16 and older.  In the United Kingdom, a widely publicized rollout of Pfizer's vaccine began on December 8. News quickly spread about two workers in the National Health Service having allergic reactions following vaccination. Both of these workers carry adrenaline autoinjectors, suggesting they have suffered reactions in the past, the Guardian reported. These kinds of autoinjectors are well known in the United States under the brand name EpiPen.

A noted vaccine expert serving on VRBPAC, Paul Offit, MD, of Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, urged the FDA and Pfizer to investigate any connection between reaction to the vaccine and known allergies. If not fully addressed, reports of the reactions seen in initial vaccinations in the UK could prove to unnecessarily frighten people who have allergies away from getting the COVID shot, he said.

Offit suggested running tests where people with egg and peanut allergies would get the Pfizer vaccine under close medical observation "to prove that this is not going to be a problem."

"This is a practical solution because this issue is not going to die until we have better data," Offit said.

More than a dozen COVID-19 vaccines have reached advanced stages of testing, including ones developed in Russia and China, according to the World Health Organization. The two leading candidates for the US market are the Pfizer/BioNTech vaccine and a similar vaccine developed by Moderna and the National Institute of Allergy and Infectious Diseases. Johnson & Johnson and AstraZeneca are among the other companies with COVID-19 vaccines in testing.

The rapid development of COVID vaccines will create challenges in testing these products. A key issue will be how and whether to continue with placebo-controlled trials, even though such research would be helpful, FDA advisers said.

The FDA tasked Steven Goodman, MD, MHS, PhD, of Stanford University with presenting an overview of considerations for continuing a placebo-controlled trial as COVID vaccines become available. Once a COVID-19 vaccine becomes available to the public, people who have received placebo in the Pfizer trial should not be allowed to immediately receive the vaccine, Goodman said.

There isn't a strong medically based argument against placebo-controlled research in COVID-19, as many people can take steps to reduce their risk for the infection, Goodman said.

"So as long as there are still important things to learn about the vaccine, placebo- controlled trials should not be regarded as unethical," Goodman said. "I think, however, they might be infeasible. And that is a big issue, because people may not be willing to either remain in the study or to enroll."

During the public comment session, a former FDA official spoke of a need for careful consideration of study volunteers' needs in designing trials of COVID-19 vaccines.

"Reasonable people can disagree over whether study subjects should have priority access to a product whose efficacy they helped demonstrate," said Peter Lurie, MD, president of the nonprofit Center for Science in the Public Interest. "But we ought to be able to agree on this: No subject who has put their body on the line in a vaccine study should be at a disadvantage in terms of vaccine access as a result of their participation."

Lurie argued against extended periods of blinded follow-up after authorization of a COVID-19 vaccine. Such a requirement would be "hard to justify ethically, if it is inconsistent with public health recommendations, particularly with rapidly rising case rates and the reported levels of effectiveness" of the Pfizer vaccine, said Lurie, who served as an associate commissioner at FDA from 2014 to 2017.

Lurie also noted the FDA staff's identification of what he called "disproportionate numbers of Bell's Palsy cases (4 in the vaccine groups vs. 0 in the placebo group)" as a matter that should continue to be monitored, including in the postmarketing phase. He raised no objections to the EUA.

Sidney Wolfe, MD, founder and senior adviser to Public Citizen's Health Research Group, also spoke at the public comment session, citing no objection to an EUA for the Pfizer vaccine. Like Lurie, he urged special consideration of people who have or will receive placebo in COVID-19 vaccine trials.

The Thursday advisory committee on the Pfizer vaccine differed from those held for many other products. The discussion focused more on how to monitor and evaluate the vaccine once approved, while advisory committees sometimes include a detailed look at whether a company has proven that its product works. One of the special advisers serving temporarily on VRBPAC, Eric J. Rubin, MD, PhD, also today published an editorial in The New England Journal of Medicine, titled "SARS-CoV-2 Vaccination — An Ounce (Actually, Much Less) of Prevention."

In the editorial, Rubin and coauthor Dan L. Longo, MD, called the Pfizer vaccine results seen so far "impressive."

"In the primary analysis, only 8 cases of Covid-19 were seen in the vaccine group, as compared with 162 in the placebo group, for an overall efficacy of 95% (with a 95% credible interval of 90.3 to 97.6%)," they write. "Although the trial does not have the statistical power to assess subgroups, efficacy appeared to be similar in low-risk and high-risk persons, including some from communities that have been disproportionately affected by disease, and in participants older than 55 years of age and those younger than 55."

Intense Scrutiny

The FDA has come under intense scrutiny this year in part because of the aggressive — and ultimately unrealistic — timelines for COVID-19 treatments promoted by the Trump administration. President Donald Trump several times suggested a COVID-19 vaccine could be approved before the November election. Many concerned physicians and scientists including Medscape Editor-in-Chief Eric Topol, MD, called on FDA staff to fight back against any bid to inappropriately speed the approval process for political reasons.

"Any shortcuts will not only jeopardize the vaccine programs but betray the public trust, which is already fragile about vaccines, and has been made more so by your lack of autonomy from the Trump administration and its overt politicization of the FDA," Topol wrote in an August open letter to FDA Commissioner Stephen Hahn, MD.

In an October interview with Topol, Hahn noted that there has been some pushback against the idea of an EUA for a COVID-19 vaccine, with some people preferring to wait for a more complete biological license application.

"When you're talking about a pandemic where people are dying, you want to expedite it as much as possible," Hahn told Topol in the interview.

On Thursday, Hahn issued a public statement about the VRBPAC meeting. Hahn said the FDA's "career staff — made up of physicians, biologists, chemists, epidemiologists, statisticians, and other professionals — have been working around the clock to thoroughly evaluate the data and information in the EUA request."

"I can assure you that no vaccine will be authorized for use in the United States until FDA career officials feel confident in allowing their own families to receive it," Hahn said.

Many clinicians offered their views on the FDA meeting during the day on Twitter.

Robert Wachter, MD, chair of the Department of Medicine at the University of California, San Francisco, who has been a vocal opponent of some of Trump's public statements on COVID-19, urged state officials to stick with the FDA's call on the Pfizer vaccine. In a tweet, he noted that officials in California and several other states have called for independent reviews of COVID-19 vaccines.

If such reviews were to delay distribution of vaccines, this would "lead to more harm than good," Wachter tweeted. "Once FDA says 'go', we should go."

https://twitter.com/Bob_Wachter/status/1337068294814093313?s=20

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