Trivalent mRNA Flu Vaccine Outperforms Standard Shots

How Does an mRNA Flu Vaccine Differ From Traditional Flu Shots?

Traditional influenza vaccines are typically manufactured by growing flu viruses in chicken eggs or cell cultures, then inactivating or weakening them. This process takes roughly six months and requires manufacturers to predict which strains will circulate before the season begins. The egg-based approach can also subtly alter viral proteins, sometimes reducing how well the vaccine matches circulating strains — a phenomenon known as egg adaptation.

Messenger RNA vaccines bypass this by delivering genetic code that instructs the body's own cells to produce influenza surface proteins, primarily hemagglutinin. The immune system recognizes these proteins as foreign and builds antibodies and T-cell responses. Because mRNA can be designed and manufactured rapidly, this platform offers the theoretical ability to better match circulating strains and to combine multiple antigens — as seen in the trivalent formulation tested in the Fluent trial.

Why Does Better Flu Protection Matter Most for Adults Over 50?

The World Health Organization estimates that seasonal influenza causes hundreds of thousands of deaths each year globally, with the heaviest toll falling on adults aged 65 and older. The U.S. Centers for Disease Control and Prevention has consistently reported that the majority of flu hospitalizations and deaths occur in older age groups, driven both by greater underlying disease burden and by age-related decline in immune responsiveness.

Standard-dose flu shots often produce weaker antibody responses in older adults, which is why high-dose and adjuvanted formulations are already recommended for those 65 and over in many countries. If mRNA flu vaccines can deliver stronger and more reliable protection in adults 50 and older — as the Fluent trial signals — they could meaningfully reduce hospitalizations during severe flu seasons and lessen pressure on health systems already strained by respiratory virus co-circulation.

What Are the Next Steps Before an mRNA Flu Vaccine Reaches Patients?

A positive Phase 3 readout is a major milestone, but regulatory approval requires comprehensive review of safety across diverse populations, durability of protection, and consistency of manufacturing. Agencies such as the U.S. Food and Drug Administration and the European Medicines Agency will assess whether the benefit-risk profile supports licensure, and advisory committees like the CDC's ACIP help shape recommendations on who should receive the vaccine and when.

Combination respiratory mRNA vaccines — covering influenza alongside SARS-CoV-2 or RSV — are also in development from multiple manufacturers. If trivalent mRNA flu vaccines prove safe and effective, they could pave the way for a single annual respiratory immunization, simplifying the schedule for older adults and improving uptake. Real-world effectiveness studies after launch will be essential to confirm trial findings hold across different flu seasons and circulating strains.