Does nirsevimab prevent RSV in infants born in October 2023?
Nirsevimab is a long-acting monoclonal antibody approved to protect infants from RSV. For a baby born in October 2023, the first RSV season typically runs from October through March. Nirsevimab is recommended for all infants under 8 months entering their first RSV season, and studies show it significantly reduces RSV-related hospitalizations and severe illness.
What the research says
Nirsevimab has been shown to provide durable protection against RSV in infants. A review of antibody strategies reports that nirsevimab reduces RSV hospitalizations by 70–90% with no evidence of antigenic escape 1. The HARMONIE trial, a large phase 3b study, found that a single dose of nirsevimab reduced hospitalizations due to RSV lower respiratory tract infection through the RSV season and up to 180 days after dosing 11. This covers the typical 5-month RSV season, so an infant born in October 2023 would be protected through the winter months. The CDC's Advisory Committee on Immunization Practices (ACIP) recommends nirsevimab for all infants under 8 months born during or entering their first RSV season, which includes October-born infants 10. A 2023-2024 US surveillance study confirmed nirsevimab effectiveness against medically attended RSV illness in infants 9.
What to ask your doctor
- Is nirsevimab recommended for my baby born in October 2023?
- When should my baby receive the nirsevimab shot to be protected for the RSV season?
- Does my baby need any other RSV prevention, like maternal vaccination?
- What are the possible side effects of nirsevimab?
- If my baby is older than 8 months at the start of RSV season, do they still need nirsevimab?
This question is drawn from common patient questions about Pediatrics and answered using cited medical research. We do not provide individualized advice.