FDA Approves First mRNA RSV Vaccine

The FDA approved the first-ever mRNA-1345 vaccine (mRESVIA) for respiratory syncytial virus (RSV) for people ages 60 and older to protect against lower respiratory tract disease, Moderna announced Friday in a press release.

“The FDA approval … builds on the strength and versatility of our mRNA platform,” Stéphane Bancel, chief executive officer of Moderna, said in the 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 marketed product, in addition to its SARS-CoV-2 mRNA-1273 vaccine (Spikevax).

The FDA’s approval of the mRNA-1345 vaccine is based on results from the phase III ConquerRSV trial. The trial enrolled around 37,000 adults ages 60 years and older and reported that the mRNA-1345 vaccine was 83.7% effective (95.88% CI 66%-92.2%) in preventing RSV-associated lower respiratory tract disease with at least two signs or symptoms. The vaccine was similarly effective (82.4%) against lower respiratory tract disease 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 than in the placebo group (47.7% vs 32.9%), with fatigue, headache, myalgia, and arthralgia being most common. Serious adverse events occurred in 2.8% of participants in both groups. Most reactions were mild to moderate in severity and were transient. Fewer than 0.1% were reported to be related to the shot.

Results of a follow-up analysis of the trial’s primary endpoint performed during FDA review were consistent with the primary analysis, according to the press release. An additional longer-term analysis also showed continued protection against RSV lower respiratory tract disease over a median of 8.6 months’ follow-up.

The mRNA-1345 vaccine should 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 administrative errors.

The vaccine consists of an mRNA sequence encoding a stabilized prefusion F glycoprotein, since the prefusion F glycoprotein is the primary target of 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’s mRNA-1273 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. Pfizer’s vaccine is also approved for pregnant people to protect newborns against the virus.