RSV: New Vaccines and the Evidence (2023-Present)

RSV disease burden in infants and older adults, the development of RSV vaccines approved in 2023-2024, clinical trial data, and current ACIP recommendations.

RNA Virus Vaccines NEW (2023) Infants & Seniors

Disease Overview & Burden

Respiratory Syncytial Virus (RSV) is a common respiratory virus that typically causes mild, cold-like symptoms but can be severe in infants and older adults. RSV is the leading cause of bronchiolitis and pneumonia in infants worldwide.

In older adults (65+), RSV can cause severe lower respiratory tract disease, leading to hospitalization and death. Prior to 2023, there was no approved vaccine for RSV in the U.S., though monoclonal antibodies (palivizumab) were available for high-risk infants.

Disease Burden

  • ~58,000-80,000 hospitalizations in children <5 years annually (U.S.)
  • ~60,000-160,000 hospitalizations in adults 65+ annually (U.S.)
  • ~14,000 deaths in adults 65+ annually (U.S.)
  • Seasonal peaks: Fall/Winter (October-March)

RSV Vaccines Approved 2023-2024

In a major milestone, the first RSV vaccines were approved by the FDA in 2023. These vaccines represent decades of research following the initial identification of RSV in 1956.

Arexvy® (GSK)

Approved May 2023

First RSV vaccine approved. Recombinant subunit vaccine containing RSV fusion (F) protein stabilized in prefusion conformation. Indicated for adults 60+.

Efficacy: 82.6% against RSV-associated lower respiratory tract disease (LRTD); 94.1% severe LRTD
Phase III: ~25,000 participants; median follow-up 6.7 months

Abrysvo® (Pfizer)

Approved August 2023

Bivalent subunit vaccine containing stabilized prefusion F proteins from RSV-A and RSV-B subtypes. First RSV vaccine with indication for both adults 60+ AND maternal immunization to protect infants.

Efficacy (adults): 66.7% against LRTD; 85.7% severe LRTD
Efficacy (infants): 81.8% against severe LRTD at 90 days; 69.4% at 6 months

mRESVIA® (Moderna)

Approved January 2024

mRNA vaccine encoding stabilized prefusion F protein. Same platform as Moderna's COVID-19 vaccine.

Efficacy: 83.7% against LRTD; 79% severe LRTD
Phase III: ~37,000 participants; median follow-up 3.7 months

Current ACIP Recommendations

Adults 60+

  • Single dose of any RSV vaccine (Arexvy, Abrysvo, or mRESVIA)
  • ACIP recommends shared clinical decision-making
  • Higher priority for those with chronic medical conditions
  • Can co-administer with influenza and COVID-19 vaccines

Maternal Immunization

  • Pfizer's Abrysvo ONLY approved for maternal use
  • Administer during pregnancy (32-36 weeks gestation)
  • Provides passive antibody protection to infants
  • Protects infants from birth through first RSV season

Note on nirsevimab (Beyfortus®)

In addition to vaccines, a new monoclonal antibody (nirsevimab/Beyfortus) was approved in July 2023 for use in infants. Unlike vaccines which stimulate the immune system, nirsevimab provides passive immunity through administered antibodies. It is recommended for all infants born during RSV season, or those entering their first RSV season, regardless of maternal vaccination status.

Sources & Citations

  • CDC. (2024). RSV Vaccination. cdc.gov/rsv
  • FDA. (2023). Arexvy Approval Letter. fda.gov/vaccines
  • ACIP. (2023). RSV Vaccine Recommendations. MMWR, 72(9), 1-27.

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