Beyfortus® (nirsevimab-alip) 50 mg and 100 mg information for OBGYNs

Fast-acting passive immunization to help prevent respiratory syncytial virus (RSV) disease, that lasts through 5 months, a typical RSV season¹⁻³*

Beyfortus is the first and only long-acting antibody indicated for the prevention of RSV lower respiratory tract disease in¹:

  • Neonates and infants born during or entering their first RSV season
  • Children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season


ACOG guidelines state that clinicians should counsel patients regarding the monoclonal antibody, Beyfortus, as another option for newborns if the maternal RSV vaccine is not received during pregnancy.⁴†

  • When possible, discussions regarding Beyfortus should include information about whether it will be available to the baby after birth
Baby icon

Infants <34 weeks

Infants born at <34 weeks should receive Beyfortus regardless of maternal vaccination status.
Baby lying down icon

Infants at risk

Infants born to mothers who still need RSV vaccination ≥14 days before birth may receive Beyfortus based on clinical judgment.

Ribbon icon

CDC/ACIP recommends Beyfortus for infants born before the RSV season, as well as those born during the season when⁵

  • The mother did not receive the RSV maternal vaccine, or
  • The mothers vaccination status is not known, or
  • The window between maternal vaccination and birth was <14 days, or
  • The healthcare provider determines the incremental benefit of Beyfortus is warranted because the infant is at increased risk, or when there are concerns about the adequacy of the maternal immune response or placental antibody transfer.

Beyfortus recommendations by CDC/ACIP and AAP⁶⋅⁷

First RSV season

Infants aged <8 months born during or entering their first RSV season are recommended to receive 1 dose of Beyfortus (50 mg for infants <5 kg and 100 mg for infants ≥5 kg) :

  • For babies born before the season, providers should target administration shortly before the start of the season for infants aged <8 months
  • For babies born during the season, Beyfortus should be administered within 1 week of birth, which can be during the birth hospitalization or in the outpatient setting

Refer to the most current CDC immunization schedule for additional immunization considerations

Supply update for 2024/2025: With AstraZeneca, we are expanding the Beyfortus manufacturing network to allow for a significant increase in supply for the coming RSV season to cover the entire US demand


Demonstrated Safety and Efficacy Profile¹

Beyfortus mAb image

Learn more about how Beyfortus works


Beyfortus is indicated for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in:

  • Neonates and infants born during or entering their first RSV season.
  • Children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season.

Important safety information


Beyfortus is contraindicated in infants and children with a history of serious hypersensitivity reactions, including anaphylaxis, to nirsevimab-alip or to any of the excipients.

Warnings and Precautions

  • Hypersensitivity Reactions Including Anaphylaxis: Serious hypersensitivity reactions have been reported following Beyfortus administration. These reactions included urticaria, dyspnea, cyanosis, and/or hypotonia. Anaphylaxis has been observed with human immunoglobulin G1 (IgG1) monoclonal antibodies. If signs and symptoms of anaphylaxis or other clinically significant hypersensitivity reactions occur, initiate appropriate treatment.
  • Use in Individuals with Clinically Significant Bleeding Disorders: As with other IM injections, Beyfortus should be given with caution to infants and children with thrombocytopenia, any coagulation disorder or to individuals on anticoagulation therapy.

Most common adverse reactions with Beyfortus were rash (0.9%) and injection site reactions (0.3%).

Please see full Prescribing Information.

Click here to learn more about Sanofi’s commitment to fighting counterfeit drugs.