Vinay Prasad is drawing heat for his personal conduct as director of the FDA’s Center for Biologics Evaluation and Research, as scrutiny grows around his decision not to review Moderna’s application for influenza vaccine candidate mRNA-1010.
Prasad is the subject of a number of internal complaints at the FDA, including “sexual harassment, retaliation against subordinates and verbally berating staff,” according to reporting from The Wall Street Journal on Wednesday, citing unnamed sources familiar with the matter.
Formerly a professor at the University of California, San Francisco, Prasad continues to live in the San Francisco Bay area and has commuted for the past year to work at the FDA in Maryland every two weeks, at a cost to taxpayers of about $65,000 per year, according to an estimate viewed by WSJ.
Prasad is also facing pushback internally over his decision to overrule FDA staffers and return a refusal-to-file (RTF) letter to Moderna on Tuesday.
In a January meeting with Prasad, FDA staff argued that a plan to block the application was the wrong approach. A review team was already assembled to review Moderna’s application, according to reporting from STAT News, and David Kaslow, director of the Office of Vaccines Research and Review within CBER, wrote an internal memo arguing against Prasad’s decision. Some staffers at the January meeting specifically pushed back against Prasad’s criticism of Moderna’s trial design, which he said “does not reflect the best-available standard of care.”
There was a “a diverse set of conclusions among the review team” looking at Moderna’s application, Health and Human Services spokesperson Andrew Nixon said in a statement emailed to Fierce Biotech.
Moderna, of course, balked at the squabble over the control arm of its study. “It should not be controversial to conduct a comprehensive review of a flu vaccine submission that uses an FDA-approved vaccine as a comparator in a study that was discussed and agreed on with CBER prior to starting,” Moderna CEO Stéphane Bancel said in a statement on Tuesday in response to the RTF.
Before Prasad took the lead at CBER in May 2025, staff at the agency had agreed to Moderna’s study designs, according to Moderna’s press release. The agency also did not raise objections when a Phase 3 study for mRNA-1010 launched in September 2024, the company noted.
Then in August 2025, a few months after Prasad joined the FDA, Moderna again met with the agency, at which point CBER staff requested additional analyses. Moderna complied, providing data from a separate Phase 3 trial that compared mRNA-1010 against an approved high-dose influenza vaccine.
“At no time in the pre-submission written feedback or meeting did CBER indicate that it would refuse to review the file,” Moderna wrote in its statement.
While Kaslow and other staffers appeared to have been ready to begin their review of mRNA-1010, Prasad apparently had other plans, overruling his team to send the RTF.
Moderna will share its fourth quarter and full-year 2025 earnings Friday morning, where analysts will likely eagerly await details about Moderna’s plans for mRNA-1010, as well as for mRNA-1083, the company’s combination influenza/COVID-19 vaccine. Last year, Moderna pulled a biologics license application for mRNA-1083 until more data from mRNA-1010 came in, on the assumption that that shot’s progress would improve mRNA-1083’s chances. The RTF for mRNA-1010 now might have the knock-on effect of disrupting mRNA-1083’s future as well.
