US Approves First mRNA Flu Vaccine, 27% More Effective, for Ages 50+

The US Food and Drug Administration (FDA) has approved the first mRNA-based influenza vaccine for people aged 50 and over. The vaccine, called mFLUSIVA, is produced by Moderna and could be available in the United States as early as this autumn.

According to the company, the vaccine was tested in a clinical trial involving more than 40,000 participants aged at least 50. Data presented by Moderna, as cited by CNN, show an efficacy approximately 27% higher than that of conventional influenza vaccines during the 2024–2025 viral season.

Moderna's Chief Executive, Stéphane Bancel, stated: "Influenza remains a major public health challenge, and mFLUSIVA offers an important new option for older Americans. This approval also reflects the continued potential of our mRNA platform to address significant public health challenges through scientific innovation."

The most commonly reported side effects include pain at the injection site, tenderness and swelling of the lymph nodes, fatigue, headaches, muscle and joint pain, nausea, vomiting, and fever.

Why mRNA technology is different

With conventional influenza vaccines, the viral strains included in the formulation are selected as early as February. mRNA vaccines, by contrast, can be produced more rapidly, allowing the composition to be adjusted closer to the start of the flu season for a better match with the strains actually in circulation. Moderna expects the new vaccine to reach the market in time for this autumn's flu season.

A path to approval not without hurdles

In February, the FDA initially declined to review Moderna's application, requesting additional clinical data, but reversed its decision approximately two weeks later and agreed to evaluate the submission. In June, the agency's independent advisory committee, made up of vaccinology specialists, voted unanimously that the vaccine's benefits outweigh its risks, recommending full approval for people aged 50 to 64 and accelerated approval for those aged 65 and over, subject to further studies.

Background: controversy surrounding mRNA vaccines in the US

Moderna already uses mRNA technology for its COVID-19 vaccines and is developing further products on the same platform. In early 2026, the European Union approved a Moderna vaccine that provides simultaneous protection against both COVID-19 and influenza. Pfizer is also working on its own mRNA influenza vaccine.

However, mRNA technology has become a subject of controversy in the United States: in August 2025, the Department of Health and Human Services cancelled 22 mRNA vaccine development projects with a combined value of approximately 500 million dollars. The US Secretary of Health, Robert F. Kennedy Jr., claimed, without scientific evidence, that mRNA vaccines do not provide effective protection against upper respiratory tract infections such as COVID-19 and influenza.

What comes next

Once the FDA approves a vaccine, its use is typically also reviewed by the CDC's Advisory Committee on Immunisation Practices, which issues official recommendations on its administration. The work of this committee has been delayed after a federal judge ruled that Robert F. Kennedy Jr.'s wholesale replacement of its members had not followed proper legal procedures. The committee's next meeting is scheduled for October.