FDA Expands Label for Moderna's mRNA RSV Vaccine to Include At-Risk Adults Aged 18 to 59 Years

The FDA has approved Moderna’s RSV vaccine, mRNA-1345 (mRESVIA), for adults aged 18–59 years who are at increased risk for respiratory syncytial virus (RSV)-related lower respiratory tract disease (LRD), extending the vaccine’s indication beyond its original approval for adults aged 60 and older. The expanded use, announced on June 12, comes ahead of the 2025–2026 respiratory virus season and reflects growing recognition of the RSV burden in younger adults with chronic health conditions, the company said in a statement.¹

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Moderna’s Phase 3 study (NCT06067230) supported the approval, demonstrating that immune responses in at-risk adults under 60 met prespecified non-inferiority criteria when compared to those seen in older adults in a prior pivotal trial.² Specifically, neutralizing antibody responses to both RSV-A and RSV-B were consistent across the subgroups aged 18 to 49 and 50 to 59 years, indicating robust and uniform immunogenicity within the expanded age cohort, according to the statement. These data were presented at the CDC’s Advisory Committee on Immunization Practices meeting in April 2025 and published in Clinical Infectious Diseases.²

Inclusion criteria for the study required prospective participants aged 18 to 59 years to gave been diagnosed with one of the following: coronary artery disease and/or congestive heart failure, chronic lung disease (COPD, persistent asthma, or other), stable type 1 or type 2 diabetes, controlled with medication.² Moderna also evaluated the safety and efficacy of mRNA-1345 among adults 18 years and older who had a kidney, liver, or lung transplant at least 6 months before enrollment and were receiving chronic immunosuppressive therapy.²

“RSV poses a serious health risk to adults with certain chronic conditions, and today’s approval marks an important step forward in our ability to protect additional populations,” Moderna CEO Stéphane Bancel, said in the statement.¹

Although RSV is typically associated with infants and older adults, data show that more than one-third of US adults aged 18 to 59 years have underlying conditions that increase their risk of severe RSV disease.^3,4 This group’s disease burden and hospitalization rates can equal or even surpass those seen in older adults,⁵ emphasizing the need for targeted prevention strategies.

mRNA-1345, a monovalent mRNA vaccine, encodes a stabilized prefusion F glycoprotein—a key viral surface protein responsible for host cell entry and a primary target for neutralizing antibodies. The vaccine uses the same lipid nanoparticle (LNP) delivery platform as Moderna’s COVID-19 vaccines, according tot he company.

The safety profile in the 18–59 age group was consistent with previous findings, with the most common adverse reactions including injection site pain, fatigue, headache, myalgia, and arthralgia.⁶

Moderna plans to have mRNA-1345 available to both eligible younger and older (60 years and older) adults during the upcoming respiratory virus season in the US.

References

Mayer EF, Falsey AR, Clark R, et al. Safety, Tolerability, and Immunogenicity of mRNA-1345 in Adults at Increased Risk for RSV Disease Aged 18 to 59 Years. Clin Infect Dis. Published online June 4, 2025. doi:10.1093/cid/ciaf292

3. Prasad N, Walker TA, Waite B, et al. Respiratory syncytial virus-associated hospitalizations among adults with chronic medical conditions. Clin Infect Dis 2021; 73(1): e158-e63.

4. Wilker E, Jiang M, Francis B, et al. Burden of chronic medical conditions that are risk factors for severe RSV among adults aged 18-59 years in the United States. Poster presented at: ESCMID; April 2025; Vienna, Austria.

5. Weycker D, Averin A, Houde L, et al. Rates of Lower Respiratory Tract Illness in US Adults by Age and Comorbidity Profile. Infect Dis Ther 2024; 13(1): 207-20.

6. Halsey G. FDA Approves Moderna's mRESVIA, First mRNA Vaccine Against RSV, for Adults Aged ≥60 Years. Patient Care Online. June 3, 2024. https://www.patientcareonline.com/view/fda-approves-moderna-s-mresvia-first-mrna-vaccine-against-rsv-for-adults-aged-60-years