Beyfortus® (nirsevimab-alip) 50 mg and 100 mg Injection is a single dose timed to the respiratory syncytial virus (RSV) season for the vast majority of infants1
The ideal timing for Beyfortus dosing is just before or near the start of the first RSV season or from birth for infants born shortly before or during the RSV season.1
Beyfortus is 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.
RSV is seasonal, with infections peaking at certain times of the year. In most of the continental US, a typical RSV season runs roughly
from fall through spring, with some exceptions such as Florida and Hawaii, where the RSV season may start earlier.1-4
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*Timing of administration for RSV protection may differ in certain areas.
Refer to the most current CDC immunization schedule for additional dosing considerations.
Additional single dose considerations
- For children undergoing cardiac surgery with cardiopulmonary bypass, an additional dose of Beyfortus is recommended as soon as the child is stable after surgery; please consult the Prescribing Information for complete information on dosing in these circumstances1
- Second season: children up to 24 months of age, regardless of body weight, who remain vulnerable1:
- 1 x 200 mg dose administered as 2 IM injections (2 x 100 mg)
Provides passive immunization that extends through 5 months, the typical length of the RSV season, regardless of birth month1,5
AAP and ACIP recommended2,6
Beyfortus is the first RSV prevention therapy approved to protect all infants in the US through their first season.1,6
First RSV season6
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):
- Providers should target administration shortly before the start of the season for infants aged <8 months
- For infants born shortly before or entering their first RSV season, Beyfortus should be administered within 1 week of birth, which can be during the birth hospitalization or in the outpatient setting
Second RSV season6
Children aged 8 to 19 months who are at increased risk of severe RSV disease and entering their second RSV season are recommended to receive 1 dose of Beyfortus (200 mg administered as 2 IM injections [2 X 100 mg]).
- Providers should target administration shortly before the start of the season for children aged 8 to 19 months who are at increased risk of severe RSV disease
Additional considerations7,8
Beyfortus is recommended for infants aged <8 months born during or entering their first RSV season:
- Whose mother did not receive the RSV maternal immunization
- Whose mother's receipt of the RSV maternal immunization is unknown
- Who were born <14 days after maternal immunization
- Beyfortus may be considered for infants whose mother received the RSV maternal immunization, and, based on the clinical judgment of the healthcare provider, the potential incremental benefit of administration is warranted
- Current recommendations for 2024-2025 are for a single lifetime dose of the RSV maternal vaccine during pregnancy and that Beyfortus should be used for infants born to mothers who received RSV vaccine during a previous pregnancy
*Beyfortus is not needed for most infants aged <8 months whose mother received the RSV maternal immunization >14 days before birth.
Due to variability in RSV seasonality, there are regional considerations for Beyfortus administration5
ACIP Regional Administration Guidelines5
- Because the timing of the onset, peak, and decline of RSV activity might vary geographically, providers can adjust administration schedules based on local epidemiology
- RSV seasonality in tropical climates (including southern Florida, Guam, Hawaii, Puerto Rico, US-affiliated Pacific Islands, and US Virgin Islands) might differ
- In Alaska, RSV seasonality is less predictable, and the duration of RSV activity is often longer than the national average duration - Providers in these jurisdictions should consult state, local, or territorial guidance on timing of Beyfortus administration
Second RSV Season Guidelines5
Infants and children aged 8 to 19 months with increased risk for severe disease who are recommended to receive Beyfortus when entering their second RSV season include:
- Children with chronic lung disease of prematurity who required medical support (chronic corticosteroid therapy, diuretic therapy, or supplemental oxygen) any time during the 6-month period before the start of the second RSV season
- Severely immunocompromised children
- Children with cystic fibrosis who have either:
1. manifestations of severe lung disease (previous hospitalization for pulmonary exacerbation in the first year of life or abnormalities on chest imaging that persist when stable), or
2. weight-for-length <10th percentile - American Indian or Alaska Native children
Single-dose, pre-filled syringe for convenient administration1
A single dose for the vast majority of infants based on weight1
Product images are representative of scale, actual size of packaging may be different.
First RSV season: neonates and infants1
The recommended dosage of Beyfortus for neonates and infants born during or entering their first RSV season is based on body weight and is administered as a single IM injection.
Recommended dosage of Beyfortus for their first RSV season
| Body Weight at the Time of Dosing | Recommended Dosage |
| <5 kg | 50 mg by IM injection |
| ≥5 kg | 100 mg by IM injection |
Second RSV season: children who remain at increased risk for severe RSV disease1
For children up to 24 months of age, regardless of body weight, who remain at increased risk for severe RSV, the recommended dosage of Beyfortus is a single 200 mg dose administered as 2 IM injections (2 x 100 mg).
Children undergoing cardiac surgery with cardiopulmonary bypass1
For children undergoing cardiac surgery with cardiopulmonary bypass, an additional dose is recommended as soon as the child is stable after surgery. Please consult the Prescribing Information for complete information on dosing in this circumstance.
Can be administered concomitantly with any childhood vaccines1
There is limited experience of Beyfortus coadministration with vaccines. In clinical trials, when Beyfortus was given with routine childhood vaccines, the safety and reactogenicity profile of the coadministered regimen was similar to the childhood vaccines given alone. Beyfortus should not be mixed with any vaccine in the same syringe or vial. When administered concomitantly with injectable vaccines, they should be given with separate syringes and at different injection sites.
Practical considerations for Beyfortus
How should Beyfortus be administered?1
- Beyfortus is for IM injection only, preferably in the anterolateral aspect of the thigh
- The entire contents of the syringe should be administered intramuscularly
- The gluteal muscle should not be used routinely as an injection site because of the risk of damage to the sciatic nerve
How should Beyfortus be stored?1
- Store in a refrigerator 36°F to 46°F (2°C to 8°C)
- Beyfortus may be kept at room temperature 68°F to 77°F (20°C to 25°C) for a maximum of 8 hours. After removal from the refrigerator, Beyfortus must be used within 8 hours or discarded
- Do not freeze
- Do not shake or expose to direct heat
- Store in original carton to protect from light until time of use
Want to Know More About Beyfortus?
Demonstrated Safety and Efficacy Profile1
AAP, American Academy of Pediatrics; ACIP, Advisory Committee on Immunization Practices; CDC, Centers for Disease Control and Prevention;
IM, intramuscular.
Important Safety Information
References: 1. Beyfortus (nirsevimab-alip). Prescribing Information. Sanofi. 2. Immunizations to protect infants. Centers for Disease Control and Prevention. August 30, 2024. Accessed November 19, 2024. https://www.cdc.gov/rsv/vaccines/protect-infants.html 3. Rose EB, Wheatley A, Langley G, et al. Respiratory syncytial virus seasonality - United States, 2014-2017. MMWR Morb Mortal Wkly Rep. 2018;67(2):71-76. 4. Surveillance of RSV. Centers for Disease Control and Prevention. August 30, 2024. Accessed November 19, 2024. https://www.cdc.gov/rsv/php/surveillance/index.html 5. Obando-Pacheco P, Justicia-Grande AJ, Rivero-Calle I, et al. Respiratory syncytial virus seasonality: a global overview. J Infect Dis. 2018;217(9):1356-1364. 6. Jones JM, Fleming-Dutra KE, Prill MM, et al. Use of nirsevimab for the prevention of respiratory syncytial virus disease among infants and young children: recommendations of the Advisory Committee on Immunization Practices—United States, 2023. MMWR Morb Mortal Wkly Rep. 2023;72(34):920-925. 7. AAP recommendations for the prevention of RSV disease in infants and children. American Academy of Pediatrics. February 21, 2024. Accessed April 4, 2025. https://publications.aap.org/redbook/resources/25379/AAP-Recommendations-for-the-Prevention-of-RSV 8. Fleming-Dutra KE, Jones JM, Roper LE, et al. Use of the Pfizer respiratory syncytial virus vaccine during pregnancy for the prevention of respiratory syncytial virus-associated lower respiratory tract disease in infants: recommendations of the Advisory Committee on Immunization Practices - United States, 2023. MMWR Morb Mortal Wkly Rep. 2023;72(41):1115-1122. 9. RSV vaccine guidance for pregnant women. Centers for Disease Control and Prevention. August 30, 2024. Accessed April 4, 2025. https://www.cdc.gov/rsv/hcp/vaccine-clinical-guidance/pregnant-people.html 10. RSV immunization guidance for infants and young children. Centers for Disease Control and Prevention. August 30, 2024. Accessed May 5, 2025. https://www.cdc.gov/rsv/hcp/vaccine-clinical-guidance/infants-young-children.html
