Washington University researchers have found evidence that an mRNA flu vaccine could offer stronger protections against influenza than a traditional flu shot.
The research, which appears in the journal Nature Immunology, is part of a larger set of studies investigating a flu shot made with mRNA technology. Instead of using a weakened or inactive virus, mRNA vaccines teach the body to produce antibodies to develop immunity.
Drugmakers introduced the first widespread mRNA vaccines during the coronavirus pandemic, and the COVID-19 immunizations remain the only mRNA vaccines currently on the market.
That could soon change, said Hanover Matz, a postdoctoral researcher at WashU who worked on a team that studied how the vaccine activated immune cells. A committee from the federal Food and Drug Administration this summer recommended the agency approve Moderna's mRNA vaccine for older adults.
"What's really cool about mRNA-based vaccines is they actually provide the genetic information to produce the proteins that might be a part of a virus," he said. "They give that instruction to your cells, the cells learn how to make the protein, and then they use that protein to train your immune system to fight the virus."
The small study looked at how well the Moderna mRNA vaccine worked compared to the traditional flu shot by studying the contents of patients' lymph nodes.
"The lymph nodes are the place where all the immune cells come together to learn how to fight the virus," Matz said. "No matter what type of vaccine you get, it's going to stimulate those cells to respond, and they're going to make something called a germinal center."
Germinal centers are sites where infection-fighting immune cells mature. In 13 people who got the mRNA flu vaccine, five developed the germinal center response in their lymph nodes. The 15 people who received the traditional flu vaccine didn't show that response.
"And so, what we found was that the mRNA-based vaccine was very, very good at producing those germinal centers in the lymph nodes," Matz said.
The study also indicated that immune response from the mRNA vaccine may last longer and protect against more strains of the flu.
Influenza is an ideal candidate for an mRNA vaccine, Matz said. The flu virus is constantly evolving, and vaccine makers are consistently playing catch-up to create immunizations that best match the circulating strains.
An mRNA vaccine would allow for a more nimble response.
"If you detect that the flu virus has changed mid-season and you want to update the vaccine, it would be much easier to update an mRNA-based vaccine and deploy ... to combat that viral mismatch."
'Some uncertainty'
The FDA committee's recommendation comes during a fraught time for mRNA vaccines and immunizations in general. Health and Human Services Secretary Robert F. Kennedy Jr. has been skeptical of vaccines and has canceled hundreds of millions of dollars in research funding for mRNA research projects.
"There has certainly been some uncertainty in the past few years about the future, particularly for mRNA-based vaccines," Matz said. "I think it's important that we recognize that the science is out there, and that these have been proven to be effective, and certainly, while improvements in that uncertainty would be great for the science community, we're still really excited to go forward with this kind of research."
He added he understands that some people may not be comfortable with mRNA vaccines. A KFF poll found that one in five people believe the false claim that mRNA vaccines alter a patients' DNA.
According to the Centers for Disease Control and Prevention, mRNA vaccines "do not enter the nucleus of the cell where our DNA (genetic material) is located, so they cannot change or influence our genes."
Public health officials have in recent years endorsed shared decision-making between physicians and patients when it comes to deciding whether or not to take particular vaccines.
"I think it's understandable that there's been some hesitation around this, and I think it's important that people always consult with their primary care physician when they're making decisions about their personal health care and vaccines," Matz said. "[But] the research is there that shows that these are safe, they're well-tolerated, and they can stimulate very effective immune responses."
Copyright 2026 St. Louis Public Radio
