The clinical hold affects Novavax’s COVID-flu combo and standalone flu vaccines, which were on the cusp of Phase III testing. The FDA’s decision stems from a report of a serious adverse event of motor neuropathy, Novavax said.
Shares of Novavax fell 16% on Wednesday as the FDA placed a clinical hold on its investigational combo COVID-19/influenza and standalone influenza vaccines after a report of a serious adverse event in a trial participant.
The standalone COVID-19 vaccine—the company’s only product currently on the U.S. market, in competition with big hitters Pfizer/BioNTech and Moderna—is not impacted by the FDA’s hold, Novavax said.
In a brief press release, Novavax said that the decision stems from a report of a serious adverse event of motor neuropathy that occurred in a Phase II trial participant outside of the U.S. The company stressed that the adverse event has not been linked to the vaccine candidates under study. The Phase II trial wrapped up in June 2023 and the company had filed with the FDA to launch a Phase III study when the adverse event was reported last month. There were no cases of motor neuropathy observed during the Phase II trial, Novavax said.
“We are working closely with the FDA to provide the necessary information that will allow them to better understand this observation and resolve the clinical hold,” said Robert Walker, Novavax’s chief medical officer, in a statement. “Our goal is to successfully resolve this matter and to start our Phase III trial as soon as possible.”
Motor neuropathy is a rare, acquired immune-mediated disorder that causes muscle weakness of the arms and legs. Cases of the adverse event were previously reported by some people who received other COVID-19 vaccines, such as Pfizer/BioNTech’s product, but the complication has not been linked to vaccination.
Novavax had a bumpy ride getting its COVID-19 vaccine to the market, earning an emergency use authorization well after market leaders Pfizer/BioNTech and Moderna. But Novavax’s shot offered an alternative to mRNA technology, gaining almost a cult-like following of people who wanted a third option in the heady days of the pandemic.
