The Food and Drug Administration has approved Moderna's mFLUSIVA, the first flu vaccine built on the same messenger RNA platform that powers the leading COVID-19 shots. The decision, dated August 5, 2026, opens the door for a new option ahead of this autumn's flu season.
The agency granted full approval for adults 50 through 64 and an accelerated approval for adults 65 and older, with the older-adult clearance tied to a confirmatory trial that Moderna has committed to run. The company said it expects doses at select US retailers during the 2026-2027 respiratory virus season.
What the trial actually showed
The pivotal Phase 3 study enrolled 40,805 adults aged 50 and up across 11 countries and compared mFLUSIVA against a standard-dose flu shot. Among participants aged 50 to 64, mRNA recipients were about 27 percent less likely to catch lab-confirmed influenza than those who received the standard-dose comparator.
Side effects were more common in the mRNA group. Injection-site pain, fatigue, headache, muscle pain and short-lived fever showed up more often than with the standard shot, though most reactions were mild to moderate and cleared within a day or two.
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Why mRNA changes the equation
Traditional flu vaccines are grown in chicken eggs, a process that takes roughly five to six months from strain selection to finished doses. mRNA vaccines skip the egg entirely and encode the target protein as a genetic instruction, a route AARP's health team describes as producible in "less than two months".
That speed matters because flu strains drift constantly. A shorter production window gives regulators more time to watch which viruses are actually circulating before locking in the season's formula. It also sidesteps the egg-adapted mutations that can chip away at effectiveness in a bad matching year.
The new shot does not replace existing options. Public-health guidance still points adults 65 and older toward high-dose or adjuvanted flu vaccines as their preferred choices for the season, and mFLUSIVA now joins that conversation rather than upending it. Anyone weighing which shot to get should talk with their doctor or pharmacist about what fits their medical history.
A bumpy road to approval
The green light closes a fraught regulatory chapter. Earlier in 2026, then-FDA biologics director Vinay Prasad issued a refusal-to-file notice, arguing the Phase 3 study had not compared mFLUSIVA against a high-dose or adjuvanted vaccine in older adults. The agency reversed course about a week later after Moderna publicly disclosed the rejection, and Prasad left the agency at the end of April.
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Moderna chief executive Stéphane Bancel framed the decision as a milestone for the mRNA platform. "The FDA approval of mFLUSIVA, our fourth approved product in the United States and the first mRNA-based flu vaccine, demonstrates the continued strength and versatility of our mRNA platform," he said in the company's approval statement.
For consumers heading into flu season, the practical picture is simple. A new tool is on the shelf for people 50 and older, older adults still have several strong options to choose from, and the annual advice from health authorities has not budged. Get a flu shot before the virus peaks.
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