From the Guidelines
Nirsevimab is recommended as a single dose for all infants under 8 months of age during their first RSV season, and for certain high-risk children aged 8-19 months during their second RSV season. The standard dose is 50mg for infants weighing less than 5kg and 100mg for those weighing 5kg or more, administered as an intramuscular injection 1. This monoclonal antibody provides passive immunity against RSV for approximately 5 months, covering the typical RSV season. Unlike traditional vaccines that stimulate the immune system to produce antibodies, nirsevimab directly provides ready-made antibodies that target the RSV F protein, preventing the virus from entering cells and causing infection.
Key Points
- The timing of administration should ideally occur before or at the beginning of RSV season, which typically runs from fall through spring in temperate climates 1.
- Side effects are generally mild and may include injection site reactions, rash, or fever.
- This preventive measure significantly reduces the risk of RSV-related lower respiratory tract infections and hospitalizations in infants.
- High-risk children aged 8-19 months who are recommended to receive nirsevimab include those with chronic lung disease of prematurity, severe immunocompromise, cystic fibrosis, and American Indian or Alaska Native children 1.
Administration Guidelines
- Providers should administer nirsevimab to infants aged <8 months and to infants and children aged 8–19 months who are at increased risk for severe RSV disease beginning shortly before the start of the RSV season 1.
- Infants born shortly before or during the RSV season should receive nirsevimab within 1 week of birth.
- Nirsevimab administration can occur during the birth hospitalization or in the outpatient setting.
Public Health Implications
- Nirsevimab can prevent severe RSV disease among infants and children aged <20 months at increased risk for severe RSV disease 1.
- Only a single dose of nirsevimab is recommended for an RSV season.
From the FDA Drug Label
The safety and effectiveness of BEYFORTUS have not been established in children older than 24 months of age. Following IM administration of nirsevimab-alip in adults, RSV neutralizing antibody levels in serum were approximately 4 times higher than baseline at 8 hours after nirsevimab-alip dosing, and maximum levels were reached by day 6 following IM administration of nirsevimab-alip in adults Duration of Protection Based on clinical data, the duration of protection offered by a single dose of BEYFORTUS extends through 5 months. The recommended use of the RSV vaccine, specifically nirsevimab, is for infants and children less than or equal to 24 months of age.
- Key Points:
- The vaccine is administered via intramuscular injection.
- The duration of protection is approximately 5 months.
- The safety and effectiveness have not been established in children older than 24 months of age or in adults 2
From the Research
RSV Vaccine Overview
- The RSV vaccine, specifically nirsevimab, is a monoclonal antibody designed to protect against Respiratory Syncytial Virus (RSV) infection.
- RSV is a major cause of lower respiratory tract infection and hospitalization in infants 3, 4, 5, 6, 7.
Recommended Use of Nirsevimab
- Nirsevimab is recommended for administration to all infants <8 months of age and for children 8 to 19 months of age who are at increased risk for severe RSV disease 5.
- The Advisory Committee on Immunization Practices (ACIP) and American Academy of Pediatrics (AAP) have recommended nirsevimab for use in infants 5.
- A single injection of nirsevimab administered before the RSV season has been shown to protect healthy late-preterm and term infants from medically attended RSV-associated lower respiratory tract infection 3.
Efficacy and Safety of Nirsevimab
- Studies have demonstrated the efficacy and safety of nirsevimab in preventing RSV infection among infants, with a significant reduction in the risk of medically attended RSV-related infection and hospitalization due to RSV infection 3, 4, 6.
- The estimated effectiveness of nirsevimab was 88.7% (95% confidence interval, 69.6-95.8) in preventing hospitalizations for RSV infection 6.
- Nirsevimab has been shown to be well-tolerated, with no significant difference in adverse events leading to death or adverse events of special interest compared to placebo 4.