The U.S. Food and Drug Administration (FDA) has granted expanded approval for Moderna’s respiratory syncytial virus (RSV) vaccine, mRESVIA, authorising its use in adults aged 18 to 59 who are at increased risk of severe illness from RSV-related complications.
This approval marks a significant step for mRESVIA, which previously held FDA approval solely for individuals aged 60 and older. Notably, the vaccine is Moderna’s first non-COVID-19 messenger RNA (mRNA)-based product to receive regulatory clearance in the U.S., and only the company’s second product overall.
The expanded indication follows the results of a late-stage clinical trial demonstrating that mRESVIA triggered a strong immune response in adults aged 18 to 59 with underlying medical conditions. Moderna reported the vaccine was well-tolerated, with no notable safety concerns.
RSV typically presents as a mild, cold-like illness but poses a serious risk to vulnerable populations, including older adults and individuals with chronic health conditions. The U.S. Centers for Disease Control and Prevention (CDC) estimates that RSV leads to between 15,000 and 20,000 hospitalisations annually among Americans aged 50 to 59.
While the FDA’s decision represents a critical regulatory milestone, the vaccine will not become available to the newly approved age group until the CDC’s Advisory Committee on Immunization Practices (ACIP) issues formal usage recommendations. The committee is scheduled to convene later this month.
Currently, the CDC recommends RSV vaccination for adults aged 75 and older, as well as for those aged 60 to 74 deemed at heightened risk. In April, ACIP’s external expert panel proposed extending those recommendations to adults aged 50 to 59 with underlying risks.
However, the advisory committee has recently come under public scrutiny. U.S. Health Secretary Robert F. Kennedy Jr. dismissed all 17 former ACIP members earlier this year, replacing them with eight new appointees. Some of the newly appointed members have previously expressed scepticism about vaccines, including those using mRNA technology—a move that has drawn concern from public health experts who fear it may erode confidence in vaccination campaigns.
Moderna’s mRESVIA joins a growing list of RSV vaccines available in the U.S., including Pfizer’s Abrysvo and GSK’s Arexvy, both of which are approved for adults aged 60 and above. Additionally, Arexvy is approved for adults 50 and older, while Abrysvo has received expanded approval for use in at-risk individuals aged 18 to 59.
Moderna previously reported mRESVIA demonstrated 83.7% efficacy in late-stage trials. However, the approved label for adults aged 60 and above cites a lower efficacy of 79% in preventing two or more RSV-related symptoms such as fever and cough.
The latest FDA approval reflects growing momentum toward protecting a broader demographic from RSV, especially amid rising awareness of the virus’s impact beyond early childhood and the elderly.
