The U.S. Food and Drug Administration approved Moderna's mFLU SIVA, the first mRNA-based seasonal flu vaccine, on Wednesday [1, 2].
This approval marks a significant pivot in how seasonal influenza is treated, moving away from traditional egg-based methods toward the faster, programmable nature of messenger RNA technology [1, 4].
The new vaccine is intended for older adults, though specific eligibility ranges vary across reports. Some data indicates the vaccine is approved for adults 50 and older [4], while other reports state it is authorized for adults between the ages of 50 and 64 [5].
Moderna has spent several years developing the mFLU SIVA platform to expand its vaccine portfolio beyond the COVID-19 pandemic. The company aims to use this technology to address not only seasonal flu, but also other complex diseases such as malaria and HIV [1].
Traditional flu vaccines often require months of production in chicken eggs, which can lead to mutations that make the final product less effective against circulating strains. mRNA vaccines are synthesized chemically, allowing for a more rapid response to the evolving nature of the virus [4].
Despite the approval, the regulatory process faced internal scrutiny. One report said that a former top vaccine regulator at the agency declined to review the Moderna shot [2]. However, the FDA ultimately granted approval for the product's use in the U.S. market [1, 3].
“The FDA approved the first mRNA‑based seasonal flu vaccine”
The authorization of mFLU SIVA validates mRNA technology as a viable tool for seasonal respiratory viruses, not just pandemic emergencies. By targeting adults 50 and older, the FDA is addressing a high-risk demographic where vaccine efficacy is often lower with traditional shots. This sets a precedent for a new generation of rapidly adaptable vaccines that can be updated more quickly to match mutating flu strains.
