(Bloomberg) — Novavax Inc. shares fell as much as 24% after US regulators placed a hold on the company’s experimental influenza and Covid-19 combination vaccines because a study volunteer developed a serious nerve disorder.
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The pause applies to Novavax’s stand-alone influenza shots and the influenza and Covid combination vaccine, it said in a statement. The company doesn’t believe causality has been established and it’s working with regulators to resolve the issue, said Robert Walker, Novavax’s chief medical officer.
Novavax shares were down 18% at 11:54 am, after earlier falling the most since July.
The patient, who developed motor neuropathy, received a combination flu and Covid shot in January 2023 as part of a study taking place outside of the US. The trial was completed in July 2023, and the participant reported the complication in September 2024.
It’s unclear when the volunteer’s health issues began. The company wasn’t available to immediately respond to questions and the US Food and Drug Administration declined to comment.
Novavax came to prominence after winning approval for a Covid-19 vaccine during the height of the pandemic, though it faced a rockier path than rivals including Pfizer Inc. and Moderna Inc. It seemed to turn a corner in May, signing a $1.2 billion licensing agreement with Sanofi that included commercializing a combination Covid-flu shot.
The company’s protein-based approach promised an effective option during the pandemic when the need for immunizations was widespread. Despite good trial results and emergency clearance from the FDA, manufacturing delays limited its use.
Last year, executives raised doubt about the company’s ability to stay in business.
(Updates shares in the third paragraph, details on Novavax in the sixth through eighth paragraphs)
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