First mRNA Flu Vaccine for Adults 50 and Older Arrives in Pharmacies

Editor’s note: This is an update to an article published in August 2026 about the FDA’s decision to approve mFlusiva.

“This is really significant,” says Paul Pottinger, MD, director of the Infectious Diseases and Tropical Medicine Clinic at UW Medical Center in Seattle, and cohost of the travel health podcast Germ & Worm. “It gives us not only a new choice, but also a more nimble, responsive way to help prevent flu,” he says.

“Since older people don’t typically respond as well to traditional flu vaccines, the idea here was to develop a shot that works better in people over 50,” says David Wohl, MD, a professor of medicine at UNC Chapel Hill in North Carolina and an infectious disease expert. Younger adults produced even stronger immune responses in earlier research, although they also had more short-term side effects after the shot, he says.

Moderna has created a vaccine finder tool to help people locate nearby immunization sites.

mFlusiva Was More Effective Than a Standard Flu Shot in Clinical Trials

Why an mRNA Flu Vaccine Is a Big Deal

Flu vaccines have to be updated every year because influenza viruses are constantly changing. Most traditional flu vaccines are grown in chicken eggs, a process that can take six months or longer, so scientists have to choose which strains to target long before flu season begins, says Pottinger. Those decisions are informed in part by which flu viruses circulate earlier in the year in the southern hemisphere.

One advantage of that approach is speed. Moderna says mFlusiva can go from strain selection to production in about two to three months, compared with roughly six months for traditional flu vaccines, says Pottinger.

“Sometimes that means we have a mismatch between what’s actually coming in the fall and what we made in the spring,” he says. With mRNA technology, vaccine makers can select strains closer to flu season, reducing the window in which the virus can change before people are vaccinated.

What Flu Strains Does mFlusiva Target?

• Standard-dose inactivated flu shots
• High-dose and adjuvanted (boosted) shots for older adults
• The FluMist nasal spray

All U.S. flu vaccines for the 2026–2027 season will protect against three viruses:

• An influenza A (H1N1) virus
• An influenza A (H3N2) virus
• An influenza B/Victoria-lineage virus

When Should You Get a Flu Shot?

For most adults, the best time to get a flu shot is October, so protection is strong when flu typically picks up in December and January and lasts into the spring, says Scott Roberts, MD, an assistant professor of infectious diseases at Yale School of Medicine in New Haven, Connecticut.

Timing can vary because of travel or other circumstances, Dr. Wohl says, “but certainly well before Thanksgiving.”

And for anyone wondering whether to seek out mFlusiva rather than another available vaccine, Pottinger offers a simple rule: “The best flu shot you can get is the one you do get.”