Nirsevimab and clesrovimab are passive immunization products that are available through the Vaccines For Children program (VFC) program. They are administered shortly before or during the RSV season (October – March in most of the continental US). No supply challenges are anticipated during the 2025-2026 season.

Product-need forecasting

As with other vaccines, your practice will need to determine how to order and stock the right amount of product. Demand from families, cost to purchase, and storage space are factors that drive how much your practice should/is able to order.  

When placing your order, consider the following in determining your order size: 

  • How many patients were born after March 1? 
    • What is the monthly average of new patients who are newborns? 
    • What % of these patients are likely to be under 5kg (if planning to use nirsevimab)? 
  • How many patients who will be 8-19 months of age during the RSV season are at high risk and meet the eligibility criteria for nirsevimab during their 2nd RSV season?   
  • What percentage of your patients are insured privately?
  • How much enthusiasm for this product is there in your practice?  What % of families do you believe will agree to RSV immunization?
  • How much storage space is in your vaccine refrigerators? (Remember that this product will be administered during fall respiratory season when other seasonal vaccines are also administered.)
  • How much cash is available to purchase this product? What financing options are available to purchase this product?  
  • How many local OB/GYN practices are administering Abrysvo?
  • How many local birthing hospitals are administering RSV immunization or are enrolled in VFC?

RSV Immunization Products

Nirsevimab (Beyfortus)

Single Dose Pre-filled Syringes

  • 50mg (0.5mL) with purple plunger rod (for infants weighing <5 kg)
  • 100 mg (1mL) with light blue plunger rod (weighing ≥5kg) 

Private Sector Cost

  • $556.13 per dose for 50mg and 100mg doses
  • $1,112.26 per dose for a 200mg dose (two 100mg doses)

Product Shelf Life: about 24 months

Ordering and Return Policies: Beyfortus ordering information

  • There is no minimum order.
  • Orders for nirsevimab placed through VaccineShop.com affords practices longer payment terms.   
  • Sanofi allows payment up until 150 days from the product shipment date if ordered directly from them. 
  • Nirsevimab can be returned after it expires, similar to other Sanofi vaccine products. 

Package Sizes

  • Five 50 mg/0.5 mL single-dose pre-filled syringes in a carton 
  • Five 100 mg/mL single-dose pre-filled syringes in a carton 

Storage and Handling

  • Store in a refrigerator at 2ËšC– 8ËšC ; DO NOT FREEZE 
  • Nirsevimab can be kept at room temperature (20ËšC – 25ËšC), for 8 hours, if protected from light. After removal from the refrigerator, nirsevimab must be used within 8 hours or discarded. 
Clesrovimab (Enflonsia)

Single Dose Pre-filled Syringe: 

  • 105 mg (0.7mL) with a pink plunger rod

Private Sector Cost

  • $556 per dose for a 105 mg dose.

Product Shelf Life: about 30 months

Ordering and Return Policies: Enflonsia ordering information

  • There is no minimum order.
  • Payment terms of up to 120 days are available through December 31, 2025 for orders placed directly through Merck. 
  • Order history and invoices for clesrovimab can be viewed by creating a Merck online account. Order payments can also be completed through the online portal.
  • Clesrovimab can be returned after it expires, similar to other Merck products. See Return Policy.

Package Sizes

  • One 105 mg/0.7mL single-dose pre-filled syringe in a carton
  • Ten 105 mg/0.7 mL single-dose pre-filled syringes in a carton

Storage and Handling

  • Store in a refrigerator at 2ËšC– 8ËšC ; DO NOT FREEZE 
  • Keep the pre-filled syringe in the original carton to protect from light until time of use
  • Clesrovimab can be kept at room temperature (20ËšC – 25ËšC), for 48 hours. After removal from the refrigerator, clesrovimab must be used within 48 hours or discarded. 
  • Do not shake

Additional considerations: 

  • The formulation of RSV immunization will not change from year to year. 
  • For additional guidance on ordering vaccines, please see the AAP Ordering Vaccines page.
  • Activated Syringe: Manufacturer-Filled Syringes (MFSs) are prepared and sealed under sterile conditions by the manufacturer. Activate an MFS (ie, remove the syringe cap or attach the needle) only when ready to use. An MFS does not contain a preservative to help prevent the growth of microorganisms. Once the sterile seal has been broken, the vaccine should be used or discarded by the end of the workday. 

Additional Information

Last Updated

09/25/2025

Source

American Academy of Pediatrics