Highlights

  • MRNA receives FDA approval to expand mRESVIA use to adults aged 18–59 with chronic conditions.
  • The company’s approval is based on Phase 3 trial data showing consistent immune response in younger adults.
  • MRNA plans to make mRESVIA available for wider adult use in the 2025–2026 U.S. virus season.

Moderna, Inc. (NASDAQ: MRNA) based in Cambridge, Massachusetts, develops mRNA-based vaccines and therapeutics for infectious diseases, cancer, rare conditions, and autoimmune disorders.

The company announced that the U.S. Food and Drug Administration (FDA) has approved an expanded indication for its respiratory syncytial virus (RSV) vaccine, mRESVIA® (mRNA-1345). The vaccine is now authorized for use in adults aged 18 to 59 who are at increased risk for RSV-related lower respiratory tract disease (LRTD), extending its previous approval granted in May 2024 for individuals aged 60 and older.

The decision follows data submitted from Moderna’s Phase 3 clinical trial (NCT06067230), which evaluated the safety and immune response of mRESVIA in adults aged 18–59 with underlying health conditions that elevate the risk of severe RSV infection. The vaccine demonstrated comparable immune responses in this group to those observed in older adults during prior studies. Neutralizing antibody levels were consistent across the 18–49 and 50–59 age subgroups, meeting the non-inferiority criteria established for regulatory approval.

RSV has traditionally been viewed as a significant health risk for infants and older adults, but growing evidence indicates that adults with chronic conditions in the 18–59 age range are also vulnerable to severe outcomes. According to data cited by Moderna, over one-third of adults in this demographic have at least one chronic condition that increases susceptibility to RSV. In some cases, the burden of illness and hospitalization rates in this population match or exceed those seen in older adults.

The vaccine was generally well tolerated among trial participants. Commonly reported side effects included pain at the injection site, fatigue, headache, muscle aches, and joint pain. Findings from the Phase 3 study were previously presented during the U.S. Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) meeting in April 2025 and were published in the journal Clinical Infectious Diseases.

mRESVIA is based on a messenger RNA (mRNA) platform and encodes a stabilized version of the prefusion F glycoprotein, a key protein that allows RSV to infect host cells. This target is shared across both major RSV subtypes—RSV-A and RSV-B—and is the focus of the neutralizing antibody response generated by the vaccine. The formulation utilizes the same lipid nanoparticle (LNP) delivery system used in Moderna’s other mRNA-based vaccines.

Moderna plans to make mRESVIA available in the United States for both newly eligible adults aged 18–59 with chronic conditions and previously approved individuals aged 60 and older during the upcoming 2025–2026 respiratory virus season.