The FDA has missed its deadline for making a decision on traditional approval for Novavax's COVID-19 vaccine, according to a source familiar with the matter.

It comes on the heels of the FDA's top vaccine scientist Peter Marks' exit from the agency, which will be effective April 5. Marks, who played a key role in developing COVID-19 vaccines during U.S. President Donald Trump's first term, was forced to resign according to media reports.

His departure led to a selloff in drugmakers' stocks on Monday and some analysts said it could put pressure on companies that currently have therapies under regulatory review.

Novavax said in February it expected a decision from the agency on its vaccine in April. The vaccine was initially authorized for emergency use in 2022. Senior leaders at the FDA said the company's application needed more data and was unlikely to be approved soon, according to the WSJ report.

Novavax, the FDA and the Department of Health and Human Services did not immediately respond for comment.

Novavax's traditional protein-based COVID shot offers an alternative technology to messenger RNA-based rivals from Pfizer-BioNTech and Moderna but has failed to make a mark in the U.S. vaccine market.