RSV Immunization Administration Frequently Asked Questions

RSV Immunization Ordering and Supply

Given nirsevimab has a shelf life of about 36 months and clesrovimab has a shelf life of about 30 months, should I purchase extra doses to have on hand knowing I can always use them next season?

Since formulations for RSV mAb products will not change year to year, leftover doses from one season can be kept refrigerated and used in the next season. However, it is also important to consider the cost of the products and potential for vaccine loss due to temperature excursions associated with natural disasters, equipment failure, etc. Choices about quantities of product to purchase are individual, by practice or institution.

How long can nirsevimab and clesrovimab be left at room temperature before discarding?

Nirsevimab can be kept at room temperature (20˚C – 25˚C) for 48 hours, if protected from light. After removal from the refrigerator, nirsevimab must be used within 48 hours or discarded. The 48 hour maximum time out of the refrigerator can be continuous or cumulative. Use Sanofi’s Stability Calculator to determine whether nirsevimab can be used based on cumulative time out of the refrigerator.

Clesrovimab may be kept at room temperature between 68°F to 77°F (20°C to 25°C) for a maximum of 48 hours. After removal from the refrigerator, clesrovimab must be used within 48 hours or discarded. The 48 hour maximum time out of the refrigerator can be continuous or cumulative.

Nirsevimab-Specific Questions

Can I administer two 50 mg doses of nirsevimab to my patient who is > 5 kg instead of a 100 mg dose?

Avoid using two 50 mg nirsevimab doses for infants weighing ≥5 kilograms (≥11 pounds), because 50 mg doses should be reserved for smaller infants who are at increased risk for severe RSV illness. Furthermore, providers should be aware that insurers may not cover the cost of two 50 mg nirsevimab doses for an individual patient.

Can we split a 100 mg manufacturer-filled syringe (MFS) of nirsevimab into two 50 mg doses?

No, nirsevimab 100 mg doses are approved for single use.  They are intended for ONE patient for ONE injection. Never administer medications from the same syringe to more than one patient, even if the needle is changed.  
 
Manufacturer-filled syringes are prepared with a single dose and sealed under sterile conditions by the manufactures. They do not contain a preservative to help prevent the growth of microorganisms.  Attempting to split 100 mg MFS into two 50 mg doses is a serious administration error that risks inadvertent contamination and infection transmission.

RSV Immunization Administration, Side Effects/Contraindications, and Timing

Because nirsevimab and clesrovimab are monoclonal antibody products, who can administer them?

Nirsevimab and clesrovimab come in prefilled syringes. In most states, anyone who can administer injections can administer nirsevimab and clesrovimab.

Can RSV immunization be co-administered with other routine vaccines?

Yes. In accordance with Immunize.org and AAP policy guidance, simultaneous administration of RSV immunization with age-appropriate vaccines is recommended. Nirsevimab and clesrovimab are not expected to interfere with the immune response to other vaccines and had similar safety and reactogenicity profiles to vaccines administered without nirsevimab or clesrovimab.

The current recommendation is that if an infant’s pregnant parent received RSV vaccine < 14 days prior to the infant’s birth, the infant should receive RSV immunization. In this scenario, is there a minimum interval between RSV vaccine (Abrysvo) administration in the pregnant parent and administration of RSV immunization (ie. nirsevimab or clesrovimab) in the infant?

No, there is no minimum interval.

If a high-risk child mistakenly received a 100 mg dose of nirsevimab when they should have received a 200 mg dose, should we have them return for the other 100mg?

If a half dose is inadvertently given, another half dose should be administered as soon as possible, but no later than the end of the season (for most of the continental US, this would be through the end of March, unless local public health authorities recommend administering during a modified time period). This counts as a 200 mg dose.

RSV Immunization Recommendations

I have a healthy patient who was 7 months old in October. They present to the clinic in November, at 8 months of age. Can they receive RSV immunization at this visit?

No. AAP recommends that only those healthy infants younger than 8 months of age at the time of administration receive RSV immunization.

Can a baby who is 9 months old but corrects to 7 months due to prematurity (delivery at 33 weeks gestational age) receive RSV immunization?

If the infant does not meet second season criteria, they would not be eligible for RSV immunization. In accordance with CDC General Best Practice Guidelines for Immunization preterm infants (infants born before 37 weeks’ gestation), regardless of birth weight, should receive RSV immunization at their chronological age using the same guidance for full-term infants and young children.  

Will infants born during the RSV season receive RSV immunization before they are discharged from the hospital?

It is recommended that infants born shortly before and during the RSV season receive RSV immunization within the first week of life, including in hospital settings. If a hospital has been unable to implement administration of RSV immunizations, the infant should receive it in an ambulatory setting as soon as possible. Not all birthing hospitals are administering RSV immunization to all newborns, and additional advocacy is ongoing. Timely and well-coordinated communication between birth hospital and the medical home is important. Equitable access to RSV immunization will require those in a community to work together.

Infants with prolonged birth hospitalizations because of prematurity or other causes should receive RSV immunization shortly before or promptly after discharge. Health care–associated RSV disease occurs; however, the incidence is unknown. Safety data for use of RSV immunization in infants with a postmenstrual age (gestational age at birth plus chronologic age) of <32 weeks are limited. To prevent health care-associated RSV disease, providers may consider administering RSV immunization to eligible hospitalized infants during their hospitalization. This decision should be based on clinical judgment, considering the potential risks and benefits as well as local RSV activity. For more information, see https://www.cdc.gov/mmwr/volumes/74/wr/mm7432a3.htm

If a patient was born towards the end of March or in April and did NOT receive RSV immunization shortly after birth, can they receive RSV immunization if they are < 8 months of age entering their second RSV season? If our facility is administering nirsevimab, should this infant receive a 100 mg or 200 mg dose?

Yes. Per AAP’s guidance, healthy infants born at the end of their first RSV season who did NOT receive RSV immunization (and whose birthing parent did not receive RSV vaccine during pregnancy) may receive one dose of RSV immunization if they are < 8 months of age entering their second RSV season.

An infant’s first dose of RSV immunization, administered at < 8 months of age, should be consistent with first season dosing (ie. 100 mg nirsevimab or 105 mg clesrovimab). 

Should a standard risk patient born in March or April (during an extended RSV season) who received a dose of RSV immunization shortly after birth, receive another dose of RSV immunization if they are < 8 months of age entering their second RSV season?

No. The infant is not eligible to receive RSV immunization since they received a dose during their first RSV season. Only children who meet high-risk criteria should receive more than one dose of RSV immunization. For more details on high-risk criteria, please see the full AAP recommendations here.

What is the guidance for high risk infants who are 19-24 months of age, particularly given nirsevimab has been FDA approved for infants and toddlers 24 months of age and younger who are at high risk for severe RSV illness?

A dose of nirsevimab is recommended for some children aged 8 through 19 months who are at increased risk for severe RSV and who are entering their second RSV season (note this is inclusive of 19 months). Nirsevimab provides at least 5 months of protection and should be offered to eligible children when entering the RSV season.

Nirsevimab is not recommended for any child who is age 20 months and older. Children ages 20 months and older have likely already experienced two RSV seasons and been infected with RSV, and thus are less likely to benefit from nirsevimab. Clesrovimab is not recommended for any child who is age 8 months and older.

What if a young infant is in our office and diagnosed with RSV that day or are within 48 hours of illness onset? Would a dose of RSV immunization be helpful to them to reduce the severity of the illness?

Nirsevimab and clesrovimab have not been studied as a treatment in infants with RSV and is not licensed for treatment of RSV disease. RSV immunization should be given prior to onset of the RSV season or as soon as possible after birth for infants born during the season to prevent severe RSV disease.

Coding and Payment

How do I code and bill for RSV immunization? Will I be paid appropriately?

See current coding and billing recommendations, including Coding Vignettes, on the Coding & Payment For RSV Immunizations page.

Does RSV immunization require insurance prior authorization?  

In most instances, RSV immunization does not require insurance preauthorization. Please report any payer concerns or hassles to the Coding & Payment Hotline.