Nirsevimab

RSV Prophylaxis in all children age <8 months in their first RSV season (typically October to March in U.S.)
1. Not needed if mother received RSV Vaccine at least 2 weeks prior to delivery (during RSV season)
2. High risk infants (e.g. Congenital Heart Disease) should receive Nirsevimab regardless of maternal RSV Vaccine
RSV Prophylaxis in all children age 8 to 19 months in their second RSV season who are at risk for severe disease
1. Single dose alternative to Palivizumab
2. See Palivizumab for high risk indications
3. High risk infants may be given Nirsevimab and stop Palivizumab if less than 5 doses of Palivizumab given

Nirsevimab is a Monoclonal Antibody that binds RSV fusion Protein, inhibiting fusion with host cell
Prevents RSV viral entry into cells and subsequent replication

Background
1. Nirsevimab is given as a single IM Injection per season ($500/dose in 2023)
  1. Contrast with Palivizumab which is dosed monthly ($1800/dose in 2023)
2. Give dose shortly before RSV season (or in the first week of life if born during RSV season)
3. May be coadministered with other Vaccinations
Season 1
1. Weight <5 kg: 50 mg IM once per season (syringe with purple plunger rod)
2. Weight >5 kg: 100 mg IM once per season (syringe with light-blue plunger rod)
Season 2
1. Give 200 mg IM (split into two 100 mg doses at different injection sites) once per season

Prevents RSV hospitalization in normal risk infants for up to 5 months after injection (NNT 48)
Similar efficacy in high risk infants as for Palivizumab (Synagis)