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FDA approves first mRNA vaccine against respiratory syncytial virus
Last reviewed: 02.07.2025
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The FDA has approved the world's first mRNA-based vaccine 1345 (mRESVIA) against respiratory syncytial virus (RSV) for people aged 60 and older to protect against lower respiratory disease, Moderna announced in a press release.
“The FDA approval... builds on the strength and versatility of our mRNA platform,” said Stéphane Bancel, CEO of Moderna, in a press release, noting that this is the first time an mRNA vaccine has been approved for a disease other than COVID-19.
The vaccine will be Moderna's second commercial product, along with the mRNA vaccine against SARS-CoV-2 (Spikevax).
The FDA approval of mRNA-1345 is based on results from the Phase 3 ConquerRSV trial. The study included approximately 37,000 adults aged 60 years and older and found that mRNA-1345 was 83.7% effective (95.88% CI 66%-92.2%) in preventing RSV-associated lower respiratory tract illness with at least two signs or symptoms. The vaccine was equally effective (82.4%) against lower respiratory tract illness with at least three signs or symptoms (96.36% CI 34.8%-95.3%).
Systemic adverse reactions were more common in those who received the vaccine compared with the placebo group (47.7% vs. 32.9%), with the most common being fatigue, headache, myalgia, and arthralgia. Serious adverse events occurred in 2.8% of participants in both groups. Most reactions were mild or moderate in severity and transient. Less than 0.1% of reactions were considered related to the vaccine.
Results from a follow-up analysis of the study's primary endpoint, conducted during the FDA review, were consistent with the primary analysis, according to the press release. An additional long-term analysis also showed continued protection against RSV-associated lower respiratory tract disease over a median follow-up of 8.6 months.
The mRNA-1345 vaccine is expected to be available in the U.S. for the 2024-2025 respiratory virus season, according to the manufacturer, and will be available in a prefilled syringe to improve ease of administration and reduce the risk of administration errors.
The vaccine consists of an mRNA sequence encoding a stabilized pre-fusion F glycoprotein, as the pre-fusion F glycoprotein is the primary target for neutralizing antibodies and is highly conserved across both RSV-A and RSV-B subtypes. The vaccine also uses the same lipid nanoparticles as the Moderna-1273 mRNA vaccine.
In 2023, the FDA approved two non-mRNA vaccines — one from Pfizer (Abrysvo) and one from GSK (Arexvy) — that can also be used in older adults. The Pfizer vaccine is also approved for pregnant women to protect newborns from the virus.