In July 2023, nirsevimab (Beyfortus), a monoclonal antibody, was approved by the Food and Drug Administration for the prevention of respiratory syncytial virus (RSV) disease in infants and children younger than 2 years of age. On Aug. 3, 2023, the Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention recommended routine use of it for all infants younger than 8 months of age born during or entering their first RSV season. Its use is also recommended for certain children 8-19 months of age who are at increased risk for severe RSV disease at the start of their second RSV season. Hearing the approval, I immediately had a flashback to residency, recalling the multiple infants admitted each fall and winter exhibiting classic symptoms including cough, rhinorrhea, nasal flaring, retractions, and wheezing with many having oxygen requirements and others needing intubation. Only supportive care was available.
RSV is the leading cause of infant hospitalizations. Annually, the CDC estimates there are 50,000-80,000 RSV hospitalizations and 100-300 RSV-related deaths in the United States in persons younger than 5 years of age. While premature infants have the highest rates of hospitalization (three times a term infant) about 79% of hospitalized children younger than 2 years have no underlying medical risks.1 The majority of children will experience RSV as an upper respiratory infection within the first 2 years of life. However, severe disease requiring hospitalization is more likely to occur in premature infants and children younger than 6 months; children younger than 2 with congenital heart disease and/or chronic lung disease; children with severe cystic fibrosis; as well as the immunocompromised child and individuals with neuromuscular disorders that preclude clearing mucous secretions or have difficulty swallowing.
Dr. Bonnie M. Word
Palivizumab (Synagis), the first monoclonal antibody to prevent RSV in infants was licensed in 1998. Its use was limited to infants meeting specific criteria developed by the American Academy of Pediatrics. Only 5% of infants had access to it. It was a short-acting agent requiring monthly injections, which were very costly ($1,661-$2,584 per dose). Eligible infants could receive up to five injections per season. Several studies proved its use was not cost beneficial.
What are the advantages of nirsevimab? It’s a long-acting monoclonal antibody. Only one dose is required per season. Costs will significantly diminish. It is recommended for all infants younger than 8 months of age born during RSV season. Those children 8-19 months at risk for severe RSV disease can receive it prior to the start of their second RSV season. During RSV season (October 1 to March 31), the initial dose should be administered to newborns just prior to hospital discharge. Older infants and newborns who did not receive it prior to hospital discharge can receive it at their medical home. Newborns should receive it within the first week of life. It is covered by the Vaccine for Children Program. Simultaneous administration with routine childhood immunizations is recommended. Finally, RSV season may vary in tropical areas (Southern Florida, Puerto Rico. etc.) and Alaska. The timing of nirsevimab administration should be based on local RSV activity provided by state and local authorities.
In addition, the FDA approved an RSV vaccine (Abrysvo) for use in adults at least 60 years of age and in pregnant women at 32-36 weeks’ gestation. The latter is administered to prevent lower respiratory tract infection in infants from birth to 6 months. Recommendations have been published for administration in nonpregnant adults. Specific information is forthcoming in terms timing of administration of nirsevimab in infants whose mothers receive Abrysvo.
RSV season is quickly approaching. Detailed recommendations for administration and FAQ questions related to nirsevimab and palivizumab can be found at https://www.aap.org or https://www.cdc.gov/vaccines/hcp/acip-recs/index.html.