mRNA Flu Vaccine Now Available for Older Adults

The nation’s first mRNA flu vaccine is now rolling out to older adults, offering a new option built on the same technology used in many Covid-19 vaccines.

FDA approval followed a rocky path

In August, the FDA approved the mRNA-based flu vaccine, called mFlusiva, for people 50 and older. It’s now available at more than 13,000 locations across the U.S., according to maker Moderna. The vaccine faced a bumpy road to approval amid a political climate unfriendly to mRNA technology: the Trump administration has cut funding for mRNA vaccine development, and the FDA initially declined to review Moderna’s application. The agency’s independent vaccine advisers ultimately voted unanimously in June that the vaccine’s benefits outweigh its risks.

Walgreens said it will offer the vaccine in limited quantities this season, with availability varying by location. CVS said it’s offering the shot to adults 50 and older upon request in select areas.

How mRNA flu shots differ from traditional ones

Traditional flu shots use inactivated or weakened virus pieces to train the immune system. mRNA vaccines instead deliver genetic instructions that prompt the body to produce a viral protein itself, triggering an immune response.

Because flu strains mutate constantly, scientists must predict which strains will dominate each season, sometimes months in advance. “Sometimes there’s a mismatch between what was selected, despite best efforts, and what the dominant circulating strain is,” said Dr. William Schaffner, an infectious disease professor at Vanderbilt University Medical Center. Traditional vaccines, grown in cells or chicken eggs, require strain selection around February, months before the shots are given. “That’s a huge challenge because it is often limiting in terms of how fast and how much vaccine we can make,” said Dr. Michael Osterholm of the University of Minnesota’s Center for Infectious Disease Research and Policy. Because mRNA vaccines can be manufactured quickly, strain selection can happen as late as May, giving researchers more flexibility to match the vaccine to circulating strains.

Two approval pathways, one for each age group

Moderna’s vaccine received standard approval for adults 50 to 64, and accelerated approval, negotiated after unusual back-and-forth with the FDA, for those 65 and older. The FDA said Moderna’s application initially lacked an “adequate and well-controlled” trial because its comparison group didn’t reflect the “best-available standard of care” for that age group; Moderna had tested the vaccine against a standard-dose flu shot, while CDC guidance recommends an enhanced-dose vaccine for adults 65 and older.

“People over the age of 65, you don’t want to compare it against a weaker vaccine,” said Dr. Gregory Poland of the Atria Research and Global Health Institute, who wasn’t involved in the study. For the 65-and-older group, Moderna presented data showing the vaccine produced more antibodies than an enhanced vaccine, and the FDA granted accelerated approval on the condition that Moderna complete a post-marketing study this flu season confirming that advantage translates into real clinical benefit. “I think the accelerated approval, with the obligation of the company to do some studies and to come back to the FDA with further data regarding effectiveness and safety, are entirely appropriate,” Schaffner said.

Weighing effectiveness against side effects

In Moderna’s study of more than 40,000 adults over 50, the mRNA vaccine was about 27% more effective than standard flu shots during the 2024-25 season. It also caused higher rates of mostly mild to moderate side effects, including injection site pain, muscle and joint pain, nausea, fever, headache and chills, which resolved within days. Serious adverse events occurred at similarly low rates across both vaccine types. People allergic to any ingredient or who’ve had Guillain-Barré syndrome after a past flu vaccine should not receive the new shot.

Poland summarized the trade-off for those 50 to 64 as “good option, moderately compelling, better efficacy trade-off is about double the rate of side effects.” For those 65 and older, he said, “we need what’s called real world effectiveness data and efficacy data.” Dr. Sean Leng, a geriatrician at Johns Hopkins University School of Medicine, said he presents both options to older patients and would recommend the mRNA shot more strongly if it proves more effective in the additional study.

Dr. Ronald Nahass, president of the Infectious Diseases Society of America, said his priority is simply getting people vaccinated. “Get a flu shot. Whatever is available,” he said. “The mRNA vaccine is perfectly fine and safe. I see no reason not to get it, and there may be some early evidence that it might even be more effective.” The flu kills an estimated 12,000 to 52,000 Americans annually, depending on the season’s severity. The shot protects only against flu; separate vaccines cover Covid-19 and RSV.

When and where to get vaccinated

The CDC’s Advisory Committee on Immunization Practices typically reviews new vaccines, but a federal judge ruled in March that Health and Human Services Secretary Robert F. Kennedy Jr. improperly replaced the committee’s members, and it hasn’t met since; a meeting is scheduled for October. In the meantime, the CDC says its July 2025 recommendations remain in effect, and most people should get any updated, FDA-licensed vaccine recommended for their age group.

Doctors generally recommend getting a flu shot before the end of October, though any time during flu season works, since flu typically peaks between December and February. Because most pharmacies order vaccines earlier in the year, mFlusiva’s availability may be limited this season; Moderna recommends using its vaccine finder tool, and Walgreens and CVS say to check with local pharmacies.

Insurance coverage remains somewhat uncertain

Without a formal ACIP recommendation, some uncertainty remains around insurance coverage. Moderna says mFlusiva should be covered by most commercial plans and Medicare Part B, and members of America’s Health Insurance Plans have said they’ll cover all ACIP-recommended immunizations at no cost through 2027. The National Association of Insurance Commissioners recommends consumers check directly with their insurer.

Why the shot matters most for older adults

Flu vaccination is especially important for older adults, who face far higher risks of severe illness. CDC data from the 2024-25 season show that adults over 50 accounted for 76.9% of flu hospitalizations despite making up just 34.4% of symptomatic illnesses, and adults 65 and older accounted for 70.6% of deaths despite only 8.8% of illnesses.

“You might have had mild flu, but you didn’t get a plastic tube down your throat and put on a ventilator. In fact, you didn’t even get hospitalized,” Poland said of the vaccine’s protective effect. Schaffner added that flu “has large ramifications that occur each year, and so everything we can do to prevent illness — particularly the most serious illness that requires admission to hospitals, admission to the intensive care unit and admissions to the cemetery — we would like to prevent as much of that as possible. And the influenza vaccine is the single best way we have at the moment, imperfect as it is, in impacting everything that flu does in society.”