Nirsevimab Recommendations for End of RSV Season from the Maine Immunization Program

Posted on April 01, 2024

Commissioner Lambrew letterhead

To: Maine Immunization Program Providers

From: Maine Immunization Program

Subject: Nirsevimab Recommendations for End of RSV Season

Date: March 29, 2024

The Maine Immunization Program would like to provide updated guidance and best practices for the end of the Respiratory Syncytial Virus (RSV) season for young children and pregnant people as the 2023-2024 respiratory season ends on March 31, 2024.

The Maine CDC and the Maine Immunization Program would like to thank our enrolled VFC provider sites for all of their hard work over the last eight months to ensure that infants and young children in Maine have access to RSV prevention. The Maine Immunization Program, with a strong partnership with the health systems, was able to enroll 20 of Maine’s birthing hospitals into the VFC program in a very short time, ensuring access to nirsevimab to those most vulnerable to RSV infection. The CDC understands the amount of time and effort that goes into ensuring immunizations are administered, stored, and handled properly. A big thank you to all the birth hospitals, health systems, and provider practices that offered RSV immunization, ensuring we are all doing our part keeping Maine’s infants and children healthy and safe.

In Maine, 2,297 doses of nirsevimab (Beyfortus – 50 mg and 100 mg) were administered to infants and young children as of Monday, March 25, 2024. The doses were administered in the following settings:

Birthing Hospitals

  • 1,111 doses of 50 mg to infants
  • 28 doses of 100 mg to young children

VFC Enrolled Provider Sites

  • 309 doses of 50 mg to infants
  • 849 doses of 100mg to young children

Total Doses Administered

  • 1,420 doses of 50 mg to infants
  • 877 dose of 100 mg to young children

RSV Immunization Seasonal Recommendations

Each age group has a recommended timing for immunization during the respiratory season. The Advisory Committee of Immunization Practices (ACIP) provided a detailed chart showing recommended timing of immunization for each population which is below. The deadline for administering RSV vaccine for pregnant people was January 31, 2024. Infants and children should receive nirsevimab until March 31, 2024. As cases of RSV continue to decline throughout the State, there will not be an extension to the 2023-2024 RSV season based off RSV State trends.

Adults aged 60 years and older may receive a single dose of RSV vaccine using shared clinical decision-making. For adults ages 60 years and older who decide with their healthcare provider to get an RSV vaccine, the best time to get vaccinated is in late summer and early fall — just before RSV usually starts to spread in the community.

RSV rec. summary

Recommendations for Healthcare Providers on the Seasonal Administration of the RSV Vaccine (Nirsevimab)

All nirsevimab products in the state of Maine have an expiration date ending in 2025. Any inventory remaining after the RSV season (end of March 31, 2024) should continue to be stored at appropriate temperature and monitored until the next RSV season.

Please ensure all administered doses of nirsevimab have been entered into ImmPact and inventory has been reconciled to reflect doses on hand to what is showing in ImmPact. Be sure to label any remaining doses and keep them in proper storage, away from other vaccines to help prevent vaccination errors.

Birthing hospitals who do not wish to continue monitoring and housing nirsevimab vaccine after the 2023-2024 season, please contact MIP so that we can arrange for transfer to hold doses until next RSV season. Provider sites may also transport to another VFC enrolled site to hold doses of nirsevimab if space is an issue. Inventory and cold chain must be up to date for both provider sites in ImmPact prior to transport. Instructions for proper vaccine transport can be found here.

Timing of Nirsevimab Administration During RSV Season

While the timing of the onset and duration of RSV season may vary, nirsevimab may be administered from October through the end of March in most of the continental United States during the respiratory season. The Advisory Committee on Immunization Practice (ACIP) provides recommendations to follow for best timing for administration of nirsevimab and the ages of infants and children who are eligible.


Storage and Handling of Nirsevimab

Proper storage and handling of nirsevimab is essential to ensure it is effective in preventing RSV disease.

Nirsevimab is supplied as pre-filled syringes for one time use only. It comes in two doses:

  • 50 mg/0.5 ml
  • 100 mg/ml

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.

Do not use nirsevimab beyond the expiration date printed on the label.

Recommendations for Healthcare Providers on the Seasonal Administration of the RSV Vaccine (Abrysvo)

Timing of RSVpreF (Abrysvo) Vaccination During Pregnancy

In most of the continental United States, pregnant people should receive RSVpreF (Abrysvo) vaccine from September through January to provide protection against RSV-associated lower respiratory tract infection in the recipient’s baby for up to 6 months after birth. The protection provided to the baby wanes over time. Because maternal RSVpreF vaccination should start 1–2 months before the anticipated start of the RSV season and continue through 2–3 months before the anticipated end of the RSV season, it is not feasible to change maternal RSVpreF vaccination timing based on year-to-year variations in RSV circulation. Thus, in most of the continental United States, maternal RSVpreF vaccination should be given from September through January, regardless of year-to-year variation in RSV circulation.

Administering RSVpreF (Abrysvo) to Pregnant People During Other Months of the Year

Administering the RSVpreF (Abrysvo) vaccine outside of the RSV season is not recommended because protection will likely begin to wane before the peak of the next RSV season. Infants will be born when RSV activity is expected to be lower, and there is less benefit relative to the cost of vaccine. If infants are expected to be born during low periods of RSV transmission, nirsevimab is recommended because it can be timed so that maximum protection is aligned with the period of high RSV transmission.

Ways to Prepare for Next RSV Season

Educating staff on RSV immunizations will help prepare your practice for the upcoming fall and winter virus season and build trust between you and your patients. Multiple studies show healthcare providers are the most trusted source of health information for their patients. They are in the best position to ensure their patients receive accurate and actionable information, including recommended immunizations.

Educating patients about the fall and winter virus season toolkit will provide patients with a full set of tools to keep themselves and their families safe from respiratory diseases this season.

For any questions, please contact the Maine Immunization Program at (207) 287-3746 or email


RSV ACIP Vaccine Recommendations | CDC

RSV (Respiratory Syncytial Virus) Immunizations | CDC

Nirsevimab Frequently Asked Questions (

Frequently Asked Questions About RSV Vaccine for Pregnant People | CDC

Frequently Asked Questions About RSV Immunization with Monoclonal Antibody for Children 19 Months and Younger | CDC

Respiratory Syncytial Virus (RSV) Prevention (

6 Tips to Prepare Your Practice and Your Patients for the Fall and Winter Virus Season (

Vaccine Storage and Handling Resources | CDC

Infant RSV Prevention At-A-Glance | CDC

RSV in Older Adults and Adults with Chronic Medical Conditions | CDC