Nirsevimab Ordering and New Product Updates for the Upcoming 2025-2026 Respiratory Syncytial Virus (RSV) Season

Maine Department of Health & Human Services sent this bulletin at 08/04/2025 11:18 AM EDT

To: Maine Immunization Program Providers

From: Maine Immunization Program

Subject: Ordering Nirsevimab and Introducing Clesrovimab for 2025-2026 Respiratory Syncytial Virus (RSV) Season

Date: August 4, 2025

Nirsevimab Ordering and New Product Updates for the Upcoming 2025-2026 Respiratory Syncytial Virus (RSV) Season

The Maine Immunization Program (MIP) would like to provide details for ordering of Beyfortus (nirsevimab) for the 2025-2026 Respiratory Syncytial Virus (RSV) season and introduce a new product, Enflonsia (clesrovimab), for infants and young children prior to the start of the fall respiratory season. Ordering for nirsevimab is now open in ImmPact and will remain available throughout the RSV season.

All remaining nirsevimab products in the State of Maine from the 2024-2025 season have an expiration date ending in 2025 or 2026. Any remaining inventory from last season should continue to be stored at appropriate temperature and used first at the start of the 2025-2026 RSV season.

Ordering for nirsevimab begins early this year and is now available for ordering in ImmPact, with no expected shortages. Notifications have been sent to all Maine’s enrolled birthing hospitals and Vaccines for Children (VFC) locations with an allocated number of doses available for ordering. Administration of RSV monoclonal antibody to infants and young children begins just before or on October 1, 2025, and goes to March 31, 2026.

Coming Soon - New RSV Monoclonal Antibody Product - Enflonsia (clesrovimab)

A new RSV monoclonal antibody product, Enflonsia (clesrovimab), was recently approved by the Advisory Committee on Immunization Practices (ACIP) during June 2025 meeting. Clesrovimab is given to all infants <8 months born during or entering their first RSV season. Administered as a single-dose, 0.7 ml pre-filled syringe, given intramuscular (IM) injection. Same dose for all infants <8 months regardless of weight.

Clesrovimab is not yet available for ordering and must go through the appropriate steps for approval prior to availability. MIP will notify enrolled VFC provider locations once more information is made available. Join our respiratory season educational webinar in September to learn more, see invite below.

Palivizumab is a short-acting monoclonal antibody product that is administered in monthly doses during the RSV season. Palivizumab is no longer routinely recommended for use. An RSV monoclonal antibody product should be used in place of palivizumab for RSV prevention.

RSV Immunization Recommendations
RSV Product	Age Recommendation	Timing for Administration
Beyfortus (nirsevimab) 50 mg – weighing less than 5 kg	All infants <8 months born during or entering their first RSV season	October 1, 2025 – March 31, 2026 Infants born during the months of April – September should receive a single dose in October
Beyfortus (nirsevimab) 100 mg – weighing 5 kg and greater	Some children age 8 months – 19 months who are at increased risk for severe RSV entering their second season	October 1, 2025 – March 31, 2026
Beyfortus (nirsevimab) 200 mg (2 x 100 mg) - no weight restrictions	Some children up to 24 months of age for their second RSV season remain at increased risk for severe RSV regardless of body weight	October 1, 2025 – March 31, 2026
Enflonsia (clesrovimab) 105 mg – no weight restrictions	All infants <8 months born during or entering their first RSV season	October 1, 2025 – March 31, 2026 Infants born during the months of April 2025 – September 2025 should receive a single dose in October
Synagis (palivizumab) - 50 mg or 100 mg monthly dosing	No longer recommended (administer an RSV monoclonal antibody product instead)	No longer recommended
Maternal Immunization for RSV
Abrysvo (Pfizer) 0.5 mL – single, one-time dose	For pregnant women at 32–36 weeks gestational age	September 1, 2025 – January 31, 2026 If Abrysvo is not administered at 32-36 weeks gestation, an RSV monoclonal antibody product should be administered directly to the newborn if born during the months of February 1, 2026 – March 31, 2026

Nirsevimab Allocation and Ordering Updates

MIP is not expecting a shortage of nirsevimab this season and will follow the same allocation model from last year to prioritize the 50 mg doses of nirsevimab for babies weighing less than 5 kg to all enrolled birthing hospitals in Maine to accommodate the most at-risk newborn population. Any remaining doses will be made available to all VFC enrolled provider sites to order under a maximum ordering quantity to ensure nirsevimab is equally distributed throughout the State of Maine.

Nirsevimab 100 mg doses for children greater than 5 kgs who are less than 8 months old and high-risk infants less than 19 months defined by the CDC, will be available for order to all enrolled provider sites at a maximum quantity of 75 doses per order.

Ordering nirsevimab MUST be placed separate from other vaccine orders. Any orders for nirsevimab placed with other vaccines in ImmPact will be denied.

Nirsevimab is Recommended For

Infants born during the seasonal administration window (October 1 through March 31) should get nirsevimab within one week after birth – ideally during the birth hospitalization.

All infants younger than 8 months of age born during RSV season or entering their first RSV season. Except in rare circumstances, most infants younger than 8 months of age do not need nirsevimab if they were born 14 or more days after their mother got an RSV vaccine.

Some children ages 8 through 19 months who are at increased risk for severe RSV disease and entering their second RSV season.

Who Should Get Nirsevimab?

Nirsevimab is recommended for infants younger than 8 months of age who were born during or are entering their first RSV season if:

The mother did not receive an RSV vaccine during pregnancy.

The mother's RSV vaccination status is unknown.

The infant was born within 14 days of maternal RSV vaccination.

Nirsevimab can be considered in rare circumstances when the healthcare provider believes the potential benefit of giving it is warranted. These circumstances may include, but are not limited to:

Infants born to pregnant people who may not mount an adequate immune response to RSV vaccination (e.g., people with immunocompromising conditions)

Infants born to pregnant people who have medical conditions associated with reduced transplacental antibody transfer (e.g., people living with HIV infection)

Infants who have undergone cardiopulmonary bypass or extracorporeal membrane oxygenation (ECMO), leading to loss of maternal antibodies

Infants with substantial increased risk for severe RSV disease (e.g., hemodynamically significant congenital heart disease, intensive care admission with a requirement of oxygen at discharge)

Some infants and young children 8 through 19 months of age who are at increased risk for severe RSV disease should receive nirsevimab shortly before the start of their second RSV season. Children receiving nirsevimab in their second RSV season should receive a single dose of 200 mg, administered through 2 separate 100 mg IM injections. Children in this high-risk group include:

Children who were born prematurely and have chronic lung disease.

Children with severe immunocompromise.

Children with cystic fibrosis who have severe disease.

American Indian and Alaska Native children.

Storage and Handling of Nirsevimab

The pre-filled syringes should be stored refrigerated between 36°F to 46°F (2°C to 8°C) and may be kept at room temperature 68°F to 77°F (20°C to 25°C) for a maximum of 8 hours.  They should be stored in the original carton to protect from light until time of use. Do not freeze or expose to heat. After removal from the refrigerator, they must be used within 8 hours or discarded. Do not use nirsevimab beyond the expiration date printed on the label.

Coadministration with Routine Childhood Vaccines

Nirsevimab can be administered without regard to timing of routine childhood vaccines. This includes simultaneous administration (i.e., same clinic day) with vaccine products. No interval between nirsevimab and live vaccines (such as MMR and Varicella) is necessary.

Documenting Nirsevimab in ImmPact

ImmPact will not have the capability to forecast for nirsevimab, due to the complexity of the ACIP recommended schedule. Providers will be responsible for using resources available to determine when the patient is due for any upcoming doses. Providers will still be required to document each dose into ImmPact within 5 business days of being administered. 

Best Practices for Upcoming RSV Season

Educating patients about the best practices for patient care during respiratory illnesses will provide patients with a full set of tools to keep themselves and their families safe from respiratory diseases this season.

Upcoming Respiratory Season Educational Webinar

Please join MIP for our annual Respiratory Season Educational Lunch and Learn Webinar on Thursday, September 18, 2025 @ 12:00 PM. This one-hour webinar will dive into the vaccines available this respiratory season through the Maine Immunization Program and Adult 317 Program. The webinar will include guest speakers from the manufactures to review the available Respiratory Syncytial Virus (RSV) monoclonal antibody products for this RSV season. Merck will present on the most up-to-date recommendations for Enflonsia (clesrovimab), the newest immunization for RSV prevention. We will also have a guest speaker from Sanofi to discuss the most up-to-date recommendations for Beyfortus (nirsevimab). MIP will also have presenters from our VFC and adult education team to review the most up-to-date recommendations for influenza and COVID-19 vaccines for the 2025-2026 respiratory season for all ages, allowing time for Q&A at the end. Please join us for this educational opportunity to learn more about which respiratory vaccines are available this respiratory season through MIP.