Canada’s Moderna mRNA Flu Vaccine Approval Comes With a Sorer Arm and a Missing Season

Health Canada has authorized two new vaccines that no Canadian can get this winter.

The two are mFLUSIVA, a standalone mRNA flu shot, and mCOFLU, a single shot that covers flu and COVID-19 together. Both are cleared for adults 50 and older, and Canada is the first country in the world to authorize both. Moderna’s chief executive, Stéphane Bancel, called it a day that does not come often: “It’s not every day that a company gets two product approvals on the same day.” A Moderna spokesperson told Global News the shots will not be part of the 2026-2027 immunization season, and the company says only that it “will engage with Canadian health authorities and immunization partners” on future availability.

The trial behind the flu shot enrolled 40,703 adults aged 50 and older across 11 countries during the 2024-25 flu season, and its results were published in the New England Journal of Medicine in May. Confirmed flu turned up in 411 of the 20,179 people who got the mRNA shot and 557 of the 20,124 who got a standard-dose flu shot. That is 2.0 per cent against 2.8 per cent, which the paper expresses as a relative efficacy of 26.6 per cent. In absolute terms, 146 fewer people caught confirmed flu out of roughly 20,000 in each arm, and more than 97 in 100 participants in both arms never caught confirmed flu at all. A September reanalysis of the FDA’s trial data, published in the Journal of Independent Medicine, put the same arithmetic another way: 137 people need the mRNA shot instead of the standard one to prevent a single confirmed case of flu, and 5,017 to prevent one hospitalization. Hospitalizations in the trial numbered four in the mRNA arm and eight in the standard arm, and the trial was not designed to measure them.

Injection-site pain was reported by 65.8 per cent of the mRNA recipients against 29.8 per cent on the standard shot, fatigue by 45.1 per cent against 20.3 per cent, headache by 37.8 per cent against 18.0 per cent, and muscle pain by 35.4 per cent against 11.6 per cent. The paper says most reactions were mild to moderate and passed quickly. The reanalysis counted any solicited reaction in 75.7 per cent of mRNA recipients against 46.7 per cent on the standard shot, and severe systemic reactions in 5.5 per cent against 0.9 per cent. Serious adverse events were close — 2.2 per cent against 1.9 per cent — with three events in the mRNA arm and two in the standard arm judged possibly related to the vaccine.

For adults 50 to 64, the US Food and Drug Administration gave mFLUSIVA a standard approval in August, on the strength of the trial above. For adults 65 and older, it gave an accelerated approval, which rests on antibody responses rather than counted flu cases: a separate study of 2,992 older adults found stronger antibody responses than a high-dose flu shot. The FDA’s approval letter makes the older age group’s approval conditional on a confirmatory trial against a high-dose vaccine, a pragmatic randomized study that was due to start on August 31. The agency’s advisory panel backed the vaccine 9-0 in June, but its staff had flagged four gaps first: the trial covered a single season, the evidence for the B/Victoria strain was inconclusive, there were no data in immunocompromised or very frail older adults, and nobody had tested giving it alongside COVID-19, RSV or pneumococcal vaccines.

The combination shot’s own trial enrolled about 8,000 adults in two age cohorts: those 65 and older got the combination or a high-dose flu shot plus Spikevax given together, and those 50 to 64 got the combination or a standard flu shot plus Spikevax. The combination met its targets, producing stronger immune responses against three flu strains and against SARS-CoV-2 in both age groups, with one exception — the B/Yamagata strain in the older cohort, a strain no longer recommended for seasonal vaccines. No serious adverse event in that trial was judged related to the combination shot. Health Canada’s product monograph for mCOFLU, dated November 4, sets out what is in the syringe: a single 0.32-millilitre dose carrying 31.7 micrograms of RNA in total, including the Omicron JN.1 spike, made without eggs and without cells, and to be given at least three months after a person’s most recent COVID-19 dose.

Three regulators have now given three different answers. The FDA approved the Moderna mRNA flu vaccine alone on August 5, the first mRNA flu vaccine licensed anywhere. The European Commission authorized the combination alone in April, under the name mCOMBRIAX. Health Canada authorized both on November 5. The paperwork behind the American decision moved fast: Moderna filed its application on December 5, 2025, the advisory panel voted in June, and the approval landed on the agency’s deadline day in August.

Moderna’s shares fell 6.5 per cent on Thursday to $241.46, before the Canadian news was announced after markets closed, then rose 5.3 per cent on Friday to $254.19 after third-quarter results beat expectations by a wide margin: revenue of $1.31 billion against $890 million expected, and earnings of 38 cents a share against an expected loss of $1.10. The stock is up 762 per cent this year. The approval was the week’s third Moderna headline, after the earnings beat and a World Health Organization recommendation that its experimental Ebola vaccine join an efficacy trial in Congo, and the market priced the earnings, not the approval.

“I had flu and COVID shots at the same time – two different arms. No issues, except a sore arm for a day. Having only one sore arm would be a bonus,” wrote Mary Ellen Warren on Facebook, under a post from the science page Unambiguous Science that drew 720 comments. “Hell yeah baby. Combined shots so I only need to have one sore arm? Sign me up!” wrote Ryan Waddell. “One poke instead of two! Works for me,” wrote Sharon Mathiason. On Threads, Jon Innes looked south: “Wishing we had a science based policy that would provide this in the USA.” The science page itself told its followers the shots would be “available for next year’s flu season.”

The enthusiasm is real, and it runs ahead of the evidence in two directions: the trial says the mRNA arm is the sorer one, so the combination saves a poke rather than a sore arm, and the shot is not available this season at all. Bancel celebrates a milestone. Two approvals in a day. The people cheer the convenience. Neither side dwells on the 26.6 per cent, or on the confirmatory trial the over-65s are still owed. The wider thread is less settled than the top comments: 720 comments split between people defending mRNA vaccines and people distrusting Health Canada and the companies, with the Allison Inquiry into vaccine injuries mentioned by name.

For this winter, Canada’s immunization committee still points everyone six months and older to the non-mRNA flu shot, with the higher-dose version for people 65 and older. It also strongly advises COVID-19 vaccination for anyone 65 and older and for residents of long-term care, retirement homes or assisted living.