By Josh Nathan-Kazis

Novavax stock was climbing again on Monday after the company expressed new confidence in the eventual approval of its Covid-19 vaccine. The shot has been caught up in the turbid health politics of the second Trump administration.

Shares of the vaccine maker have gyrated violently in recent weeks after the Food and Drug Administration missed its April 1 deadline to announce a decision on full approval of the company's Covid vaccine. The agency first cleared the vaccine under what's known as an accelerated approval in 2022.

The missed FDA approval deadline, the first since the start of the Trump administration, raised fears that Health Secretary Robert F. Kennedy Jr., a prominent vaccine skeptic, was meddling in the review process.

For Novavax, approval for the shot would bring a significant boost, including a $175 million milestone payment from Sanofi, the French drugmaker that licensed its Covid shot last year. Novavax hasn't issued revenue guidance for 2025, but that payout would account for a quarter of the revenue Wall Street analysts expect the company to earn this year.

Novavax shares have risen and fallen rapidly since the missed approval deadline. The stock has bounced between $5.01 and $7.35 per share.

On Friday, The Wall Street Journal reported that the FDA asked Novavax to run a new randomized clinical trial of the Covid shot, something other Covid vaccine makers had not needed to do to win full approval of their vaccines.

Novavax had said on Wednesday, April 23, that the FDA asked the company to commit to "generate additional clinical data" after the Covid shot was approved. On Monday, Novavax put out a new statement saying the FDA requested the company run an additional clinical trial of the shot after it was approved, and said the request was "not unusual."

"We believe our application is approvable upon alignment on the details of the [postmarketing commitment]," Novavax said. "We look forward to continued engagement with the FDA."

The statement suggested that Novavax still thinks it can get its shot approved in the near term, even with the new requirement, though it wasn't immediately clear how to square Novavax's assertion with the Journal report that the company will need to run a new randomized trial of the shot. A randomized efficacy trial of a vaccine is a major undertaking and not a standard postmarketing requirement for approved vaccines.

Neither Novavax nor the U.S. Department of Health and Human Services immediately responded to a request for comment.

Novavax shares climbed as much as 10% in early trading on Monday, but the surge moderated, and shares were up 3% in late morning trading. The American depositary receipt of Novavax's partner Sanofi was up 1.5%.

A post on the social media site X from FDA commissioner Dr. Marty Makary added to the confusion. In a Friday post, Makary cited the Journal article on the clinical trial requirement for Novavax, and wrote: "To be clear, this is a new product that Novavax is trying to introduce to the market with a study of a different product from 2021. New products require new clinical studies."

Novavax and other Covid vaccine makers consider the current shots to be updated versions of the original shots and not new vaccines. That appears to be how the FDA thought of the shots in the past. Moderna and Pfizer both have full approval for their Covid shots, though both those approvals were based on efficacy trials run on the original versions of their shots early in the pandemic.

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com

This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.

(END) Dow Jones Newswires

April 28, 2025 11:38 ET (15:38 GMT)

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