12:05 PM EDT, 04/10/2025 (MT Newswires) -- Novavax ( NVAX ) shares were down sharply Thursday after US Health and Human Services Secretary Robert Kennedy Jr., raised doubts about the effectiveness of the company's Covid-19 vaccine.

Novavax's ( NVAX ) Nuvaxovid Covid-19 vaccine is currently available under conditional approval and is awaiting full approval from the US Food and Drug Administration, which was expected by April 1, Bloomberg reported.

In a CBS News interview on Wednesday, Kennedy attributed the delay to the vaccine's single-antigen composition, saying such vaccines have "never worked" for respiratory diseases.

"We are actually shifting our priorities to multiple antigen vaccines. And [National Institutes of Health] is already working on a number of those," Kennedy said.

Shares of other Covid-19 vaccine manufacturers including Moderna ( MRNA ) , BioNTech (BNTX), Inovio Pharmaceuticals ( INO ) and Pfizer ( PFE ) were also falling after Kennedy's comments.

Novavax ( NVAX ) didn't immediately respond to a request for comment from MT Newswires.

Price: 5.19, Change: -1.56, Percent Change: -23.05