Moderna's mRNA Flu Vaccine, mFLUSIVA, Gains FDA Approval for Adults 50+

Moderna announced Thursday that the Food and Drug Administration (FDA) has approved its flu vaccine, mRNA-1010, marketed as mFLUSIVA, for use in all adults 50 years of age and older. This decision follows a unanimous vote by FDA advisors in June recommending the vaccine's approval.

The advisory committee's recommendation was based on findings from trials involving nearly 44,000 participants, which demonstrated mFLUSIVA's superior efficacy compared to existing seasonal flu shots and a favorable safety profile. The FDA had previously set an August 5 deadline for its final determination on the vaccine.

Despite the strong endorsement from FDA advisors, the path to approval for mFLUSIVA encountered significant hurdles. Current Health Secretary Robert F. Kennedy Jr., a vocal opponent of vaccination, has actively sought to impede vaccination efforts, including canceling a federal campaign for flu shots during a severe flu season.

Secretary Kennedy has also expressed hostility towards mRNA vaccines, previously labeling the mRNA COVID-19 vaccine as the “deadliest vaccine ever made” and cutting hundreds of millions of dollars in federal research grants for mRNA technology. In February, Trump appointee Vinay Prasad, an ally of Kennedy, initially refused to review mFLUSIVA, citing concerns that Moderna had not compared its vaccine’s efficacy against the appropriate existing vaccine.

Moderna publicly countered Prasad's justification, asserting that FDA officials had previously approved its trial designs. The FDA subsequently overturned Prasad’s rejection the following week, and Prasad departed from the agency at the end of April amidst a series of controversial actions.

At the June advisory committee meeting, experts highlighted the benefits of an mRNA-based flu vaccine. The mRNA platform, identical to that used in Moderna's COVID-19 vaccines, allows for rapid adjustments and updates to vaccine design and facilitates faster, scalable production compared to traditional flu vaccines. Conventional flu vaccines, produced in fertilized chicken eggs, require six to eight months, whereas mRNA vaccines can be manufactured in one to two months.

Moderna CEO Stéphane Bancel celebrated the approval in a statement, emphasizing the “continued strength and versatility of our mRNA platform.” He added that “Flu remains a significant public health challenge, and mFLUSIVA provides an important new option for America’s seniors,” and that the approval “reflects the ongoing potential of our mRNA platform to help address important public health challenges through continued scientific innovation.”

However, uncertainties persist for the vaccine, primarily due to the current status of the Centers for Disease Control and Prevention's (CDC) advisory panel. A federal judge ruled in March that most of the anti-vaccine allies appointed to the panel by Kennedy were unqualified, issuing a temporary injunction that reversed their appointments and many of Kennedy’s changes to federal vaccine recommendations. The Trump administration is appealing this ruling.

As a result of the ongoing litigation, the CDC’s Advisory Committee on Immunization Practices (ACIP) has not convened. Without an ACIP recommendation for mFLUSIVA’s clinical use for the upcoming flu season, healthcare providers may face ambiguity regarding which adults over 50 should receive the vaccine. Additionally, it remains unclear whether mFLUSIVA will be covered by federal vaccine programs or private insurance companies, which are mandated to cover ACIP-recommended vaccines. Moderna anticipates mFLUSIVA will be available for the 2026–2027 flu season, though The Wall Street Journal reported that Wall Street analysts do not foresee substantial sales until the 2027–2028 season.