mRNA Flu Vaccine Offers Broader, Longer-Lasting Immunity
A new study led by researchers at Washington University School of Medicine in St. Louis has found that an investigational mRNA influenza vaccine, developed by Moderna, helps the immune system recognize a wider range of influenza viruses than today’s standard flu shot, offering stronger and potentially longer-lasting protection. The findings, published June 15 in Nature Immunology, could mark a significant step forward in the fight against seasonal influenza.
A Persistent Challenge
Approximately 1 billion people worldwide contract influenza each year. While flu shots reduce hospitalizations and deaths, their effectiveness varies significantly from season to season. Standard vaccines are manufactured months in advance using egg-based production, and when the circulating strains do not match the vaccine strains, efficacy can drop from around 60% in a good year to as low as 19%. A vaccine capable of eliciting broader immunity could address this longstanding vulnerability.
How mRNA-1010 Works
The vaccine, designated mRNA-1010, delivers genetic instructions that prompt the body to produce proteins from four influenza strains, triggering an immune response against intruding viruses. It is currently under review by the U.S. Food and Drug Administration, with a target decision date of August 5, 2026. If approved, it would become the first mRNA-based influenza vaccine.
In a separate Phase 3 clinical trial, Moderna found that mRNA-1010 reduced the risk of illness by 26.6% more than the standard flu vaccine in older adults. The new study, published in Nature Immunology, sought to understand the biological mechanisms behind this improved protection.
Study Design and Key Findings
Researchers led by senior author Ali Ellebedy, PhD, the Leo Loeb Professor in the WashU Medicine Department of Pathology & Immunology, tracked 75 adults aged 20 to 50 across the 2022-2023 and 2023-2024 flu seasons. Approximately half received mRNA-1010, while the other half received Fluarix, a standard approved flu shot. Both vaccines targeted the same strains recommended by the World Health Organization.
Analyzing blood samples, the researchers found that participants who received the mRNA vaccine produced more flu-specific antibodies and more flu-specific memory B cells—immune cells that remember past infections and can rapidly generate antibodies against pathogens. Among 13 people receiving mRNA-1010, five developed flu-specific germinal center responses in the lymph nodes that persisted for the full 26 weeks of the study. In contrast, no persistent immune responses were observed in the 15 participants who received the traditional flu shot.
“We are seeing that the mRNA flu vaccine doesn’t just boost the immune system’s response to what it has already seen, it can help expand and diversify the antibody response, covering a broader range of flu strains,” said Ellebedy. “If we can make flu immunity broader and more durable, that could mean fewer hospitalizations and deaths, which translates into a major impact on public health.”
Broader Antibody Recognition
From four weeks after vaccination until the six-month mark, antibodies from mRNA vaccine recipients recognized and bound to many diverse flu strains across decades of viral evolution, particularly those known to cause the most widespread illness. Antibodies from standard vaccine recipients bound to fewer divergent virus strains.
First author Hanover Matz, PhD, a postdoctoral research associate in Ellebedy’s laboratory, explained the significance: “Influenza is constantly evolving to evade our immune system. But if we can develop vaccines that activate diverse B cells that target a broad portfolio of flu viruses, we have a better chance of avoiding strain mismatches and potentially even reducing the frequency with which the vaccine is needed.”
Implications and Outlook
The study demonstrates that mRNA technology, which proved transformative during the COVID-19 pandemic, may offer similar advantages for influenza vaccination. Beyond producing broader immune responses, mRNA vaccines can be manufactured more quickly than traditional egg-based vaccines, potentially enabling faster responses to emerging viral strains.
The findings also carry significance for the broader vaccine landscape. Moderna is developing combination vaccines that target flu alongside COVID-19 and RSV, and the success of mRNA-1010 could accelerate these efforts.
However, questions remain. The FDA’s decision on mRNA-1010, expected by August 5, 2026, will determine whether this technology reaches the public. Researchers also note that the durability of protection observed—26 weeks—will need to be assessed across full flu seasons and in larger, more diverse populations.
A Note on the Story’s Origin
This story was covered internationally, including by China’s People’s Daily, which republished the report from Science and Technology Daily. While the headline in some outlets framed the research as Chinese-developed, the study was conducted entirely by US-based researchers at Washington University School of Medicine in St. Louis on a vaccine developed by US-based Moderna, Inc.
As the FDA review deadline approaches, the scientific community and the public alike will be watching closely to see whether mRNA-1010 becomes the first mRNA-based flu vaccine—potentially transforming how the world fights influenza.