US FDA pauses Novavax's trial of combo COVID-flu shot on safety concerns

By Bhanvi Satija

(Reuters) -The U.S. Food and Drug Administration has put on hold a trial of Novavax's COVID-influenza and its standalone flu vaccines after a participant who took the combination shot reported nerve damage, the company said on Wednesday.

Its shares plunged as much as 24%, and if losses hold, it would wipe off nearly $400 million from the vaccine maker's market capitalization.

The stock drop also reflect concerns on whether the hold would impact Novavax's partnership with French drugmaker Sanofi, according to one analyst.

Novavax said a participant enrolled in a mid-stage study of the combination vaccine last month reported symptoms of motor neuropathy, or damage to the nerve cells that control muscles or movement. The person was given the vaccine in January last year.

The company said it was not yet established that the vaccine had caused the safety event and it was working with the FDA to resolve the pause.

"Our goal is to successfully resolve this matter and to start our Phase 3 trial as soon as possible," Chief Medical Officer Robert Walker said.

At least two analysts said it was too early to draw a conclusion. Jefferies analyst Roger Song said motor neuropathy was not a side effect seen in any older trials of Novavax's shots.

Still, the pause fueled investor worries over the company's growth as its COVID-19 shot, Novavax's only approved product, faces low demand after a late entry into the U.S. market.

The company in May had signed a deal worth at least $1.2 billion with Sanofi to co-sell Novavax's vaccine in most countries and use the COVID shot along with its own flu vaccines to develop a combination shot.

Sanofi said the clinical hold has "nothing to do with" its partnership with Novavax. Outside of the agreement, the companies can individually develop their own flu-COVID vaccines and other products, it said in an e-mailed statement.

"Fundamentally this doesn't seem to have a direct impact on Novavax's partnership with Sanofi," TD Cowen analyst Brendan Smith said.

Investors will closely monitor what additional data the FDA asks for, he said.

(Reporting by Bhanvi Satija and Leroy Leo in Bengaluru; Editing by Anil D'Silva, Arun Koyyur and Sriraj Kalluvila)