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The U.S. Food and Drug Administration has approved Moderna’s mRNA-based flu vaccine for people aged 50 and older — a complete reversal from an earlier refusal to review the shot.
The approval clears the way for the vaccine to be available in the U.S., likely next year, but won’t affect a separate, ongoing Health Canada review of Moderna’s application for approval of the same vaccine in Canada.
Nonetheless, health-care experts in Canada welcomed the development.
“The reason I think this is exceptionally good news is because the mRNA vaccines seem to be very protective of people who are older, with comorbidities, and people who are immunocompromised,” said Dawn Bowdish, an immunologist and professor in the department of medicine at McMaster University in Hamilton, Ont.
The FDA approval was based on data from a late-stage trial involving more than 40,000 adults aged 50 and older, which showed the shot was 26.6 per cent more effective than a licensed standard-dose flu vaccine.
That’s highly meaningful for a fast-evolving respiratory disease that can be deadly to vulnerable groups such as infants or older adults, said Jason Kindrachuk, an associate professor of medical microbiology and infectious diseases at the University of Manitoba in Winnipeg and the Canada Research Chair on emerging viruses.
Health Canada has authorized Moderna to launch a clinical trial for a vaccine targeting the Bundibugyo form of the Ebola virus, which continues to surge throughout the Democratic Republic of the Congo, with more than 1,700 known deaths and 3,800 infections recorded since May. The announcement makes Canada just the second country to launch a Phase 1 clinical trial for a Bundibugyo vaccine candidate after the U.K.
“Something that is more efficacious is obviously going to decrease not only the toll on people’s health, but also the toll on hospitals and health-care clinics across the country and certainly across the globe, which I think is a big consideration,” Kindrachuk said.
The public can be “very dismissive” of the impact of influenza, Kindrachuk said, but the virus kills tens of thousands of people in the U.S. every year and thousands in Canada.
“So having something that’s available, or at least an additional armament in the cupboard to be able to provide protection against something we know is going to have a public impact on an ongoing basis — that, to me, is critical.”
The shot, mFlusiva, was given a traditional approval by the FDA for adults aged 50 to 64, and an accelerated approval for those 65 years and older. Moderna has agreed to run an additional study and submit more data in adults 65 and older to confirm the vaccine’s benefit in that age group.
Departure from traditional vaccines
Health experts say higher overall effectiveness, coupled with the potential for a shorter manufacturing timeline, could be game changers in fighting the flu.
Traditional flu vaccines are grown in chicken eggs, their specific makeup determined months ahead of flu season by a World Health Organization panel effectively trying to guess which flu strains will be most prominent by the time the growing process is complete.
Messenger-based RNA vaccines, which rose to prominence during the COVID-19 pandemic, give our cells instructions to build a piece of a virus protein that is harmless on its own but allows the immune system to build defences against the active virus.
They can also be manufactured more quickly, said McMaster’s Bowdish, “which should give us more ability to adapt to new strains as it becomes apparent which ones will affect the Northern Hemisphere.”
Scientists accelerated efforts around mRNA research with the onset of the COVID-19 pandemic — with reviews showing the billions of doses given worldwide were safe and effective — boosting efforts to use the technology against other diseases, including cancer and influenza.
Earlier this week, Health Canada authorized a clinical trial for an mRNA vaccine to fight the Bundibugyo form of the Ebola virus currently raging in the Democratic Republic of the Congo.
Data from the Public Health Agency of Canada released Friday shows the number of flu outbreaks across the country is still rising, and hospitalizations due to the virus are set to surge in the coming weeks. Dr. Jennifer Vines from the B.C. Centre for Disease Control tells Hanomansing Tonight why it’s never too late to get the influenza vaccine, despite concerns that this year’s available vaccine isn’t a good match for the current predominant strain.
Vaccine controversy at FDA
The Moderna mRNA approval comes amid ongoing upheaval within the U.S. administration around vaccines. U.S. Health Secretary Robert F. Kennedy Jr. has been critical of vaccines, particularly those using mRNA technology, and scrutiny of vaccines at the FDA has increased since he took the role.
Moderna’s application to the FDA for MFlusiva was refused in early February and then accepted for review a week later after Moderna made modifications to the application.
In 2025, Moderna also withdrew an application for a combo COVID-flu shot after the agency sought additional evidence demonstrating the effectiveness of its flu component.
Former FDA commissioner Marty Makary and former vaccine chief Vinay Prasad were forced to resign earlier this year amid controversies over vaccine and rare-disease drug reviews, including Moderna’s flu vaccine application. Acting commissioner Kyle Diamantas has since sought to steady the agency and rebuild industry confidence.
