A key advisory panel to the U.S. Food and Drug Administration is preparing to cast a vote on whether the benefits of Moderna’s new flu vaccine outweigh its potential risks in older adults — a review that follows a notable reversal by regulators who had initially moved to reject the drugmaker’s application.
Moderna is pursuing two different types of approval for the vaccine, known as mFlusiva. The company is seeking standard approval for adults between 50 and 64 years old, and a conditional, accelerated approval for adults 65 and older — a pathway that would require Moderna to carry out additional studies confirming the vaccine actually works. The company has agreed to conduct that follow-up research and provide more data for the older age group if it receives approval.
The advisory committee review is taking place against a backdrop of recent turmoil at the FDA. Both the agency’s commissioner, Marty Makary, and its vaccine chief, Vinay Prasad, recently left the agency following a string of controversies surrounding vaccine and rare-disease drug reviews — including the handling of Moderna’s flu shot application. Senior FDA officials had previously stated that Moderna put patients at risk by not using the preferred higher-dose flu vaccine as the comparison treatment in its clinical trial for adults 65 and older.
Acting Commissioner Kyle Diamantas has been working to steady the agency and rebuild its relationship with the biotechnology industry following months of disruption.
In briefing materials released ahead of the advisory meeting, FDA staff reviewers indicated that immune response data from Moderna’s flu shot could support a finding of effectiveness in adults 65 and older. However, those same documents raised concerns about the vaccine’s performance in people with weakened immune systems and very frail elderly individuals, both of whom were left out of the clinical trials.
Moderna’s own submission stated that its vaccine performed better than standard-dose flu shots among adults aged 50 to 64. A separate, smaller study also showed the vaccine produced a strong immune response when compared with a high-dose flu vaccine in adults 65 and older.
Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, offered perspective on the review process. “Every year when we approve flu vaccines, we don’t have efficacy data. So I think the question will be whether or not they thought that the immunogenicity study was big enough,” he said.
If the FDA grants approval, mFlusiva would become the first seasonal flu vaccine in the United States developed using mRNA technology — the same faster-production platform behind some COVID-19 vaccines. It would enter a competitive market alongside flu vaccines from Sanofi, GSK, CSL Seqirus, and AstraZeneca.
One key difference from conventional flu vaccines is that mFlusiva does not use chicken eggs in its production process. Moderna says this allows manufacturers to more closely match the vaccine to flu strains currently circulating and reduces the time between selecting the strain and making the vaccine available.
The FDA is expected to issue its final decision on the vaccine by August 5. One analyst at Jefferies, Andrew Tsai, does not anticipate Moderna generating flu vaccine revenue until 2027, but projects $750 million in combined U.S. flu and COVID-flu combo vaccine sales by 2030.
