Respiratory syncytial virus (RSV) already represents a blockbuster business with Sanofi reporting that Beyfortus (nirsevimab) hit global sales of €1.7 billion (roughly $1.77 billion) in its first full year on the market in 2024.
3D rendering of nirsevimab. Image courtesy of Sanofi.
Beyfortus protects infants from lung infections caused by RSV
Beyfortus can help prevent a serious lung disease associated with RSV in children up to 24 months old. Beyfortus is a preventative antibody administered as an injection and is “backed by more than 40 real-world studies involving 250,000 immunized infants,” according to Thomas Triomphe, Executive Vice President of Vaccines at Sanofi.
Sanofi is shipping Beyfortus starting early in the third quarter of this year to ensure availability as immunizations begin in early fall. Sanofi has tripled the production of Beyfortus since 2023. The current supply of Beyfortus matches the total number of doses expected to be administered for the 2024-2025 season. Sanofi says production is ongoing and anticipates that it will meet demand for the upcoming RSV season.
Beyfortus has a half-life of 71 days, making it the longest-acting monoclonal antibody for RSV in infants. It is the only RSV immunization designed to protect all infants born before or during RSV season, regardless of underlying health conditions.
RSV market maturation
The RSV treatment landscape may be nascent, but it is an increasingly crowded market.
Palivizumab (Synagis), approved in 1998, is indicated for the prevention of serious RSV-associated lower respiratory tract disease in high-risk infants and young children. Nirsevimab (Beyfortus), which won an FDA nod in July 2023, covers neonates and infants entering their first RSV season and vulnerable children up to 24 months old. Clesrovimab (Enflonsia), approved today, is a monoclonal antibody administered as a single dose to protect infants up to one year of age during their first RSV season.
As for vaccines, Arexvy (GSK), approved in May 2023, is the first RSV vaccine for individuals aged 60 and up. Pfizer’s Abrysvo, approved that same year in the same age group, won expanded approval in August 2023 for use in pregnant individuals to protect infants up to six months old. Meanwhile, Moderna’s mRNA-based mRESVIA, which won approval in May 2024, is another vaccine for adults 60 and older.
Pipeline therapies include AstraZeneca’s IVX-A12, a bivalent combination vaccine targeting both RSV and human metapneumovirus, which has completed phase 2 trials. In addition, Clover Biopharmaceuticals’ SCB-1019, a non-adjuvanted bivalent RSV vaccine candidate, is undergoing a phase 1 revaccination study in older adults previously vaccinated with Arexvy.
About RSV
RSV, a common virus that causes infections of the lungs and respiratory tract, is highly contagious and is more severe in infants and older adults. Two out of three infants will develop an RSV infection during their first year of life. The virus is the main cause of lower respiratory tract disease and the leading cause of hospitalization in infants globally. Each year in the United States, an estimated 58,000–80,000 children younger than 5 years old are hospitalized due to RSV, according to the CDC. RSV season typically occurs from November to March.
Filed Under: Biologics, Cardiovascular, Immunology, Pediatrics
