Respiratory Syncytial Virus (RSV) Immunization: Information for Health Care Providers

Infant RSV antibody products are injectable monoclonal antibodies that prevent severe RSV disease in infants and some young children. Monoclonal antibodies do not activate the immune system, as would occur with infection or vaccination (active immunization). Rather, the antibodies themselves protect against disease (passive immunization).

Because infant RSV antibodies do not activate the immune system, protection is likely most effective in the weeks after they are given and wanes over time. RSV antibodies do not provide long-term immunity to RSV disease but instead provide protection to infants in the 5 months after administration, when they are most at risk of getting severe RSV disease. As children get older, they are less likely to get severe symptoms from RSV infection.

There are two infant RSV antibody products available: clesrovimab and nirsevimab. Either product is recommended for use in infants younger than 8 months born during or entering their first RSV season. There is no preferential recommendation for use of these products in this age group. For children ages 8 through 19 months who are at increased risk of severe RSV disease and entering their second RSV season, only nirsevimab is recommended.

Proper storage and handling of infant RSV antibody products is essential to ensure they are effective in preventing severe RSV disease. Nirsevimab and clesrovimab are both supplied as pre-filled syringes.

Pre-filled nirsevimab or clesrovimab syringes should be stored refrigerated between 36°F to 46°F (2°C to 8°C). They should be stored in the original carton to protect from light until time of use. Do not freeze, shake, or expose to heat.

Nirsevimab 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, nirsevimab must be used within 8 hours or discarded. Do not use nirsevimab beyond the expiration date printed on the label.

Clesrovimab may be kept at room temperature 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. Do not use clesrovimab beyond the expiration date printed on the label.

Route

Administer infant RSV antibody intramuscularly. The preferred site of administration is the anterolateral thigh region for both clesrovimab and nirsevimab. Do not administer infant RSV antibody intravenously, intradermally, or subcutaneously.

Dosage

For nirsevimab:

• Age less than 8 months
  • 50 mg for infants weighing <5 kg [<11 lb], administered as single dose
  • 100 mg for infants weighing ≥5 kg [≥11 lb], administered as single dose
• Age 8 through 19 months
  • 200 mg, administered as two 100 mg injections

For clesrovimab:

• 105 mg/0.7 mL – Same dose for all infants younger than 8 months regardless of weight. Not recommended for infants 8 months of age and older.

Seasonal administration

See "Additional Considerations" in RSV Immunization Guidance for Infants and Young Children for more information on seasonal administration of RSV antibody.

Administration with vaccine products

Infant RSV antibody products 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 RSV antibodies and live vaccines (such as MMR and varicella) is necessary.

There is limited experience with administering infant RSV antibody with vaccine products. However, infant RSV antibody is not expected to interfere with the immune response to vaccine products. In clinical trials, when RSV antibody was given concomitantly with routine childhood vaccines, the safety and reactogenicity profile of the co-administered regimen was similar to the childhood vaccines given alone.

Access the IIS for RSV preventive antibodies.

To prevent severe RSV disease in infants, either maternal RSV vaccination (Pfizer's Abrysvo) or infant immunization with a long-acting RSV monoclonal antibody (nirsevimab or clesrovimab) is recommended.

RSVpreF (Abrysvo, Pfizer) consists of a recombinant RSV F protein antigen (based on both the RSV-A and RSV-B subtypes), stabilized in the prefusion conformation (preF). The vaccine is supplied as a single-dose vial of 120 μg of lyophilized preF antigen component (60 μg from RSV-A, 60 μg from RSV-B) to be reconstituted with the accompanying vial of sterile water diluent component. A single dose after reconstitution is approximately 0.5 mL. Consult the package insert for proper storage and handling details, shelf life, and reconstitution instructions: Package Insert – ABRYSVO (fda.gov).

Proper vaccine storage and handling practices play an important role in protecting individuals and communities from vaccine-preventable diseases. For general recommendations and guidance, see Vaccine Storage and Handling. Provided below is guidance for the RSVpreF vaccine.

Pfizer's vaccine is supplied in a kit with three components:

• Vial of Lyophilized Antigen Component (a sterile white powder)
• Prefilled syringe containing Sterile Water Diluent Component
• Vial adapterRefer to the manufacturer's package insert for specific instructions on reconstituting the vaccine: Package Insert – ABRYSVO (fda.gov).

Before reconstitution:

• Store vaccine and diluent refrigerated between 2°C and 8°C (36°F and 46°F).
  • Store these components in their original package and keep them together in the refrigerator to optimize organization.
• Never freeze the vaccine or diluent.

After reconstitution:

• Immediately administer the vaccine; you should prepare the vaccine only when ready for use. If you do not immediately administer the vaccine, there are some minor differences in storage:
  • Store the reconstituted vaccine ONLY at room temperature (15⁰C to 30⁰C / 59⁰F to 86⁰F).
  • Do NOT refrigerate. This is very different than other reconstituted vaccines. Typically, storage after reconstitution is refrigerated storage only or refrigerated or room temperature storage. For this vaccine, do NOT put it back in the refrigerator.
  • Never freeze the vaccine or diluent.
• Once you've reconstituted the vaccine, you begin a 4-hour beyond-use date clock. This means that you must use the reconstituted vaccine within 4 hours; otherwise discard it.

This section provides a summary of guidance for administering RSVpreF vaccine (Abrysvo, Pfizer) for use in pregnant women, including route, number of doses, and co-administration with other vaccines.

Do not use RSVpreF vaccine (Abrysvo, Pfizer) beyond the expiration date printed on the label.

Route

Administer RSVpreF vaccine (Abrysvo, Pfizer) intramuscularly. The preferred site of administration is the deltoid region of the upper arm. Do not administer RSV vaccine intravenously, intradermally, or subcutaneously.

Number of doses

RSVpreF vaccine (Abrysvo, Pfizer) is currently approved and recommended for administration as a single dose. Sufficient evidence does not exist at this time to determine the need for additional doses in subsequent pregnancies.

Administration with other vaccines

Pregnant women can receive RSV, Tdap, COVID-19, and influenza vaccines at the same clinic visit when the vaccines are recommended. CDC's general best practice guidelines for immunization indicate that age-appropriate vaccinations can be given at the same visit, unless there is a specific reason not to.

Administration errors

Pfizer's Abrysvo is the only RSV vaccine recommended for pregnant women. GSK's Arexvy and Moderna's mResvia are not approved for use in pregnancy. If a pregnant woman receives Arexvy or mResvia in error, the following guidance is provided:

• For pregnant women who have received Arexvy or mResvia in error, do not give the pregnant woman a dose of the Pfizer RSV vaccine (Abrysvo).

• Inform the recipient of the vaccine administration error.

• Experts suggest no special monitoring for the pregnant woman beyond routine prenatal care is needed.

• If Arexvy or mResvia is given in error to a pregnant woman, the infant should receive infant RSV antibody for RSV prevention.

• Providers should consult with the state immunization program and/or immunization information system (IIS) to determine how the dose should be entered into the IIS.

• Determine how the error occurred and implement strategies to prevent it from happening again. Potential strategies to help prevent these errors include:
  • Order and stock vaccine products that fit best with your patient population. Avoid stocking multiple products, if possible.
  • If more than one RSV vaccine products are stocked, label Arexvy or mResvia with "Do NOT administer to pregnant women."
  • Educate staff on vaccine recommendations. If more than one RSV products are stocked, train staff about the differences in preparation and indications.
  • Follow medication administration best practices – read and check the vaccine product label at least 3 times and ask another staff member to confirm that it is the correct vaccine product for the patient.
  • If referring pregnant women to another vaccine provider, tell the provider to only administer Abrysvo (Pfizer) vaccine and to confirm the vaccine product prior to administration.
• Healthcare providers are encouraged to report administration errors to the Vaccine Adverse Event Reporting System (VAERS), even if there is no adverse health event associated with the error.

CDC recommends a respiratory syncytial virus (RSV) vaccine for pregnant women to protect their babies from severe RSV disease.

There are three RSV vaccines licensed by the Food and Drug Administration (FDA) for use in adults. CDC recommends RSV vaccination for all adults ages 75 and older and for adults ages 50 –74 who are at increased risk of severe RSV illness.

GSK's Arexvy consists of a recombinant RSV F protein antigen (based on the RSV-A subtype), stabilized in the prefusion conformation (preF), and AS01_E adjuvant. The AS01 adjuvant system is the same used in GSK's recombinant zoster vaccine (RZV, Shingrix), but at a lower dose. The vaccine is supplied as a single-dose vial of 120 μg of lyophilized preF antigen component to be reconstituted with the accompanying vial of AS01_E adjuvant suspension component. A single dose after reconstitution is 0.5 mL. Consult the package insert for proper storage and handling details, shelf life, and reconstitution instructions: Package Insert – AREXVY (fda.gov).

Pfizer's Abrysvo consists of a recombinant RSV F protein antigen (based on both the RSV-A and RSV-B subtypes), stabilized in the prefusion conformation (preF). The vaccine is supplied as a single-dose vial of 120 μg of lyophilized preF antigen component (60 μg from RSV-A, 60 μg from RSV-B) to be reconstituted with the accompanying vial of sterile water diluent component. A single dose after reconstitution is approximately 0.5 mL. Consult the package insert for proper storage and handling details, shelf life, and reconstitution instructions: Package Insert – ABRYSVO (fda.gov).

Moderna's mResvia consists of a single 0.5 mL-dose vial containing 50 μg of nucleoside modified mRNA encoding the RSV F glycoprotein (monovalent, based on the RSV-A subtype), stabilized in the prefusion conformation (pre-F protein). Consult the package insert for proper storage and handling details, shelf life, and more: Package Insert – MRESVIA (fda.gov).

Proper vaccine storage and handling practices help prevent errors, protect patients, and assure vaccine efficacy – all critical for protecting individuals and communities from vaccine-preventable diseases. For general recommendations and guidance, see Vaccine Storage and Handling. Provided below is guidance specific to RSV vaccines.

GSK's AREXVY

Arexvy is supplied in two vials that must be reconstituted prior to administration. One vial is a lyophilized antigen component, and the second is a liquid diluent adjuvant suspension. You MUST use the diluent provided by the manufacturer. Refer to the manufacturer's package insert for specific instructions on reconstituting the vaccine: Package Insert – AREXVY (fda.gov).

Before reconstitution:

• Store vaccine and diluent refrigerated between 2°C and 8°C (36°F and 46°F).
  • Store these in their original package and keep them together in the refrigerator to optimize organization.
• Never freeze the vaccine or diluent.
• Protect the vial from light.

After reconstitution:

• Immediately administer the vaccine; you should prepare the vaccine only when ready for use.
• If you do not immediately administer the vaccine, there are some minor differences in storage:
  • Store the reconstituted refrigerated between 2°C and 8°C (36°F and 46°F) OR at room temperature [up to 25°C (77°F)]. The difference is due to the allowance of storage at room temperature.
  • Never freeze the reconstituted vaccine, and
  • Protect it from light.
• Once you've reconstituted the vaccine, you begin a 4-hour beyond-use date clock. This means that you must use the reconstituted vaccine within 4 hours; otherwise discard it.

PFIZER's ABRYSVO

Abrysvo is supplied in a kit with three components: a vial of lyophilized antigen component (a sterile white powder), a prefilled syringe containing sterile water diluent component, and a vial adapter. Refer to the manufacturer's package insert for specific instructions on reconstituting the vaccine: Package Insert – ABRYSVO (fda.gov).

Before reconstitution:

• Store vaccine and diluent refrigerated between 2°C and 8°C (36°F and 46°F).
  • Store these components in their original package and keep them together in the refrigerator to optimize organization.
• Never freeze the vaccine or diluent.

After reconstitution:

• Immediately administer the vaccine; you should prepare the vaccine only when ready for use. If you do not immediately administer the vaccine, there are some minor differences in storage:
  • Store the reconstituted vaccine ONLY at room temperature [15⁰C to 30⁰C (59⁰F to 86⁰F)].
  • Do NOT refrigerate. This is very different than other reconstituted vaccines. Typically, storage after reconstitution is refrigerated storage only or refrigerated or room temperature storage. For this vaccine, do NOT put it back in the refrigerator.
  • Never freeze the vaccine or diluent.
• Once you've reconstituted the vaccine, you begin a 4-hour beyond-use date clock. This means that you must use the reconstituted vaccine within 4 hours; otherwise discard it.

MODERNA's mRESVIA

mResvia is supplied as a pre-filled syringe that contains a frozen suspension that must be thawed prior to administration. During storage, minimize exposure to room light, and avoid exposure to direct sunlight and ultraviolet light. Refer to the manufacturer's package insert for specific instructions on storage and thawing: Package Insert – mRESVIA (fda.gov).

Frozen storage

Store frozen between -40°C to -15°C (-40°F to 5°F).

Storage after thawing

Storage at 2°C to 8°C (36°F to 46°F):

• Pre-filled plastic syringes may be stored refrigerated between 2°C to 8°C (36°F to 46°F) for up to 30 days prior to use.

Storage at 8°C to 25°C (46°F to 77°F):

• Pre-filled plastic syringes may be stored between 8°C to 25°C (46°F to 77°F) for a total of 24 hours after removal from refrigerated conditions. Discard the pre-filled syringe if not used within this time. Syringes should not be returned to the refrigerator after being thawed at room temperature.
• Total storage at 8°C to 25°C (46°F to 77°F) must not exceed 24 hours.
• Do not refreeze once thawed. Do not shake.

Do not use any RSV vaccine beyond the expiration date printed on the label.

Route

Administer RSV vaccine intramuscularly. The preferred site of administration is the deltoid region of the upper arm. Do not administer RSV vaccine intravenously, intradermally, or subcutaneously.

Number of doses

The RSV vaccine is not currently an annual vaccine. CDC recommends only a single dose of an age-appropriate RSV vaccine for all adults ages 75 and older and for adults ages 50–74 with increased risk of severe RSV disease.

Administration with other vaccines

Coadministration of RSV vaccines with other adult vaccines during the same visit is acceptable. Available data on immunogenicity of coadministration of RSV vaccines and other vaccines are currently limited. Coadministration of RSV and seasonal influenza vaccines met noninferiority criteria for immunogenicity, with the exception of the FluA/Darwin H3N2 strain when Arexvy was coadministered with adjuvanted quadrivalent inactivated influenza vaccine. RSV and influenza antibody titers were somewhat lower with coadministration; however, the clinical significance of this is unknown.

Administering RSV vaccine with one or more other vaccines at the same visit might increase local or systemic reactogenicity. Data are only available for coadministration of RSV and influenza vaccines, and evidence is mixed regarding increased reactogenicity. Data are lacking on the safety of coadministration with other vaccines that might be recommended for persons in this age group, such as COVID-19 vaccines; pneumococcal vaccines; adult tetanus, diphtheria, and pertussis vaccines; and the recombinant zoster vaccine (the recombinant zoster vaccine and Arexvy contain the same adjuvant). When deciding whether to coadminister other vaccines with an RSV vaccine, providers should consider whether the patient is up to date with currently recommended vaccines, the feasibility of the patient returning for additional vaccine doses, risk for acquiring vaccine-preventable disease, vaccine reactogenicity profiles, and patient preferences. Post-licensure efficacy and safety monitoring of coadministered RSV vaccines with other vaccines will further direct guidance.

CDC recommends a single dose of RSV vaccine for certain adults to help prevent serious RSV infection and hospitalization.