Active Maternal Immunization

Employs bivalent prefusion f protein-based vaccine, Abrysvo.
Administered strictly between 32 and 36 weeks gestation.
Administration recommended from September through January to protect infants during seasonal peak.
Induces maternal antibodies that transfer transplacentally to protect infants.
Reduces infant hospitalization risk by 68% and severe outcomes requiring mechanical ventilation by 82% within first 3 months.
Arexvy and mResvia remain strictly contraindicated during pregnancy.

Passive Infant Immunization

Utilizes monoclonal antibodies targeting respiratory syncytial virus fusion protein.
Long-acting monoclonal antibodies preferred over short-acting options due to prolonged half-life and single-dose convenience.
Administered to infants under 8 months entering first respiratory syncytial virus season if maternal vaccine not received.
World health organization recommends either maternal vaccination or infant monoclonal antibodies, avoiding simultaneous use for identical mother-infant pair.
Exceptions permitting dual use include maternal vaccination less than 14 days before delivery, maternal immunocompromise, and infant cardiopulmonary bypass.

Feature	Nirsevimab	Clesrovimab	Palivizumab
Mechanism	Binds site zero on fusion protein locking prefusion conformation.	Binds site iv on fusion protein.	Targets fusion protein.
Duration	Long-acting, 63-73 days half-life.	Long-acting.	Short-acting, 19-27 days half-life.
Dosing strategy	Weight-based dosing.	Single fixed dose.	Weight-based dosing.
First season dose	50 mg if <5 kg; 100 mg if >=5 kg.	105 mg fixed dose.	Monthly injections.
High-risk second season	200 mg dose recommended.	only indicated till 8 months of age	Monthly injections.
Coadministration	Safe with routine infant vaccines including Bacille Calmette-Guerin and pentavalent.	Safe with routine infant vaccines.	Safe with routine infant vaccines.