Summary: Moderna mRNA flu vaccine review rejected by FDA

Why It Matters: The FDA's top vaccine regulator blocked the review of a new mRNA flu vaccine. This happened even though the company followed previous FDA guidance and agency scientists supported the review.

What Changed:

• The FDA issued a "refusal to file" letter for Moderna’s mRNA-1010 flu vaccine.
• Regulator Vinay Prasad overruled internal FDA scientists who wanted to proceed with the review.
• The FDA now claims the trial's "comparator vaccine" was not the best standard of care, despite approving the trial design twice before.
• New reports suggest the regulator intends to use similar "blindside" tactics against other drug developers.