FDA committee pans wide COVID-19 booster rollout, but backs narrower use

An FDA advisory committee (AdCom) on Friday voted 16-2 against a third dose of Pfizer and BioNTech's COVID-19 vaccine Comirnaty for use in the general population, dealing a blow to the Biden administration's push to begin broadly dispensing boosters in the US as of next week. The agency had asked the AdCom to consider whether data submitted by the companies supported approval of an extra Comirnaty shot for all fully-vaccinated people ages 16 and up.

After rejecting that proposal, AdCom panelists began discussing narrower options, and unanimously recommended booster doses for people 65-plus and high-risk populations. The FDA last month allowed third doses of either Comirnaty or Moderna's mRNA-1273 to be given to certain immunocompromised individuals, citing data that this "small, vulnerable group" might benefit from the increased protection. However, top US health officials later called for that to be extended to the general population, arguing immunity levels appear to fall over time. They also highlighted concerns about weaker protection against the Delta variant.

Vigorous debate, but panel says data not there yet

"There are very clear populations where a booster may be appropriate, such as elderly or immunocompromised," remarked AdCom panelist Michael Kurilla at Friday's meeting, but "it's not clear to me that the data we're seeing right now is applicable or necessary for the general population." Committee member Ofer Levy echoed the opinion, saying a booster would be "likely beneficial…for the elderly, and may eventually be indicated for the general population. I just don't think we're there yet in terms of the data."

Panelist Cody Meissner said "I don't think a booster dose is going to significantly contribute to controlling the pandemic…and I think it's important that the main message we transmit is that we've got to get everyone two doses." Meanwhile, CDC official Amanda Cohn noted that "at this moment, it is clear that the unvaccinated are driving transmission in the US."

In a paper published in The Lancet days before the AdCom meeting, a group of scientists, including two departing vaccine officials at the FDA, opposed widespread distribution of boosters for now, arguing that available data show vaccine protection against severe disease persists, even as the effectiveness against mild disease wanes over time. They also said governments should instead focus on inoculating unvaccinated populations.

Awaiting FDA, CDC decisions

In briefing documents released ahead of the meeting, FDA staff scientists struck a rather neutral tone, but also concluded that "currently US-licensed or authorised COVID-19 vaccines still afford protection against severe…disease and death." A final FDA decision could come in a matter of hours, while the Centers of Disease Control and Prevention (CDC) has scheduled a two-day meeting next week to discuss plans to distribute the third shots in the US.

Prior to the vote, US Surgeon General Vivek Murthy, who was one of the senior health officials who supported widespread boosters, said "this initial plan [will] be contingent on the FDA and the CDC's independent evaluation. We will follow that evaluation and their recommendations." Meanwhile, White House coronavirus response coordinator Jeff Zientz stated "we've been working through the last few weeks, intensely with our partners, our governors, state, and local health officials, federal pharmacy programmes, the community health centres, to ensure that we are ready for next week."

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