The U.S. Food and Drug Administration (FDA) has approved mFlusiva, the first mRNA vaccine for seasonal influenza, ending a complicated review process for Moderna’s new flu shot.
The approval comes as the federal government has taken a generally cautious or unfavorable position toward mRNA vaccines. The U.S. Department of Health and Human Services (HHS) canceled $500 million in funding for mRNA vaccine development, affecting 22 projects. A key vaccine advisory committee was also restructured to include members who have been publicly critical of mRNA vaccines.
Health Secretary Robert F. Kennedy Jr. has falsely described mRNA-based COVID-19 vaccines as the “deadliest vaccines ever made” and incorrectly claimed that mRNA vaccines perform poorly against upper-respiratory viruses.
Does the FDA’s approval of an mRNA flu vaccine indicate that federal attitudes toward the technology are changing? Not necessarily, experts told Live Science.
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“I don’t read this as a shift in the administration’s stance on mRNA,” Jeff Coller, a professor of RNA biology and therapeutics at Johns Hopkins University, said in an email.
Coller is also a co-founder of the Alliance for mRNA Medicines, an international organization that supports mRNA research and development. He said the approval nevertheless shows that the FDA’s regulatory process can still evaluate mRNA vaccine evidence despite political opposition to the technology.
“What the approval does signal, and I think this is the more useful story: the statutory machinery still works when it is allowed to run,” Coller said. “For companies and investors deciding whether to keep building in this space in the United States, that matters more than any statement from HHS.”
Why the mRNA flu vaccine approval process was delayed
Moderna developed the new seasonal flu vaccine, called mFlusiva. The company submitted its application to the FDA in February, but the agency initially refused to review the materials.
Reporting by STAT News later indicated that career FDA scientists had intended to review the application. However, they were reportedly overruled by Dr. Vinay Prasad, then director of the FDA’s Center for Biologics Evaluation and Research (CBER). Live Science has contacted the FDA for comment.
“It’s been a little tortured,” Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, said of the process.
In April 2024, before Moderna began its final clinical trial, the company discussed its plans with the FDA. The agency confirmed in writing that the trial design was acceptable. But after Moderna submitted its application based on the trial data, the review was initially rejected under Prasad’s leadership, Offit said.
The FDA reversed that decision within a month, and Prasad later left the FDA in April.
“That refusal was reversed fifteen days later,” Coller said. “Nothing about the evidence changed in those fifteen days.” In his view, the key difference was the decision-making by FDA leadership.
After the application moved forward, the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) reviewed mFlusiva’s safety and effectiveness. The committee unanimously recommended approval for adults ages 50 and older, and the FDA subsequently approved the vaccine for that population.
“They’re experts in the field,” Offit said of VRBPAC members. He served on the committee from 2017 to 2025. “It’s a pleasure to go to those meetings because, you know, it’s the way it’s supposed to work,” he said.
Unlike the Advisory Committee on Immunization Practices (ACIP), which advises the Centers for Disease Control and Prevention (CDC), VRBPAC has not undergone a major membership overhaul since Kennedy became health secretary. The FDA committee does have a number of vacancies, but its current members include specialists in infectious diseases, immunology, global health and genetics.
mRNA flu vaccines can be manufactured faster than conventional influenza vaccines, and clinical trials suggest that mFlusiva may provide stronger protection for some adults.
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What happens next for the new mRNA flu vaccine?
Following FDA approval, mFlusiva’s data must be reviewed by the CDC, which issues recommendations about how the vaccine should be used and which groups should receive it. Typically, ACIP reviews the evidence before providing guidance to the CDC. However, the committee’s role in this case remains uncertain, Offit said.
ACIP is currently involved in a lawsuit that prompted a federal judge to freeze several recent committee changes. Those changes included Kennedy’s appointment of new members and a significant revision to the childhood immunization schedule.
ACIP could issue new vaccine guidance if enough members are appointed to address the current vacancies and legal uncertainty, but that has not yet occurred. The CDC could also release recommendations for mFlusiva without ACIP’s assistance, because the agency has the authority to do so.
“I don’t know,” Offit said when asked whether the CDC would issue recommendations. “Robert F. Kennedy Jr. has ultimate say, and he’s a science denialist and an anti-vaccine activist. So I don’t know.” Offit predicted that Kennedy “will do nothing to encourage vaccination, period, independent of what the vaccine technology is.”
Because the FDA has licensed mFlusiva, the vaccine could technically be used without specific CDC recommendations, Offit said. However, the absence of CDC guidance could affect insurance coverage and access.
Having an mRNA flu vaccine available for the upcoming influenza season could provide an important alternative to existing vaccines. Clinical trial results suggest mFlusiva may offer greater protection, particularly for adults ages 50 to 64.
More data will be collected from adults ages 65 and older to compare mFlusiva with high-dose flu vaccines designed for seniors. Existing evidence, including studies measuring antibody levels, has been encouraging, Offit said.
mRNA flu vaccines also have potential manufacturing advantages. They can be produced in roughly half the time required for conventional influenza vaccines and may be adapted more quickly to match the flu strains expected to circulate each season.
During the 2025-2026 flu season, influenza caused at least 390,000 hospitalizations and 24,000 deaths in the United States. Flu vaccination remains the best way to reduce the risk of severe influenza illness and death.
The FDA’s approval of mFlusiva demonstrates that federal regulators can still review mRNA vaccine data and approve products that meet the required standards. But the decision does not necessarily represent a broader change in the government’s position on mRNA technology, Coller said.
“An approval is a legal determination on one application. It tells you the data met the standard, which everyone involved in reviewing it already knew,” he said. “A genuine shift would look like the 22 canceled mRNA contracts being restored, or a retraction of the claim that these vaccines fail against respiratory viruses. As far as I know, neither has happened.”
This article is for informational purposes only and is not intended to provide medical advice.
Source: www.livescience.com