Healthcare Providers: RSV Vaccination for Pregnant People

Recommendations for maternal RSV vaccination

CDC recommends a respiratory syncytial virus (RSV) vaccine for pregnant people to protect their babies from severe RSV disease. Pregnant people should get a single dose of Pfizer’s bivalent RSVpreF vaccine (Abrysvo) during weeks 32 through 36 of pregnancy during September through January.

To prevent severe RSV disease in infants, either maternal RSV vaccination or infant immunization with RSV monoclonal antibody is recommended. Most infants will not need both.

Timing of administration

CDC recommends one dose of Pfizer’s bivalent RSVpreF vaccine (Abrysvo) during RSV season for people who are 32 through 36 weeks pregnant.

In most of the continental United States, pregnant people should receive RSV vaccine from September through January so that their babies are protected against severe RSV disease at birth.

However, RSV seasons can vary in different parts of the United States. Local, state, and territorial health departments can determine the best times to start and stop administration of RSV vaccines in their jurisdictions. This is especially important in Alaska, parts of Florida, Hawaii, Puerto Rico, U.S. Virgin Islands, Guam, and the U.S.-affiliated Pacific Islands, where RSV seasonality can be different from most of the continental U.S.

Contraindications and precautions

RSVpreF (Abrysvo, Pfizer) should not be administered to a person with a history of severe allergic reaction, such as anaphylaxis, to any component of this vaccine. Information about Abrysvo can be found in the manufacturer’s package insert.

Adults with a minor acute illness, such as a cold, can receive RSV vaccination. Moderate or severe acute illness, with or without fever, is a precaution to vaccination; vaccination should generally be deferred until the patient improves.

To learn more, see ACIP Contraindications Guidelines for Immunization, General Best Practice Guidelines for Immunization.

Composition of RSVpreF vaccine (Abrysvo, Pfizer)

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).

Vaccine efficacy

Data from clinical trials show that the recommended RSVpreF (Abrysvo) vaccine is safe and efficacious for use in pregnant people to prevent severe RSV disease in infants from birth through 6 months of age.

Two randomized, double-blinded, placebo-controlled clinical studies were conducted. In the one study, approximately 100 pregnant people received the maternal RSV vaccine and approximately 100 pregnant people received a placebo. In the second study, approximately 3,600 pregnant people received a single dose of the maternal RSV vaccine and approximately 3,600 pregnant people received a placebo.

In the phase 3 clinical trial, maternal RSV vaccine reduced the risk of the baby being hospitalized for RSV by 68% and having a healthcare visit for RSV by 57% within 3 months after birth. In the same trial, the RSV vaccine reduced the risk of the baby being hospitalized for RSV by 57% and having a healthcare visit for RSV by 51% within 6 months after birth.

The maternal RSV vaccine reduced the risk of severe RSV disease by 82% within 3 months and by 69% within 6 months after birth. In this trial, severe RSV disease was defined as RSV infection that results in tachypnea, hypoxemia, use of a high-flow nasal cannula or mechanical ventilation, admission to an intensive care unit, or unresponsiveness.

Vaccine safety

In clinical trials, the most-reported side effects by pregnant people who received the RSVpreF (Abrysvo) vaccine were pain at the injection site, headache, myalgia, and nausea.

Preterm birth

People in the clinical trial who received the maternal RSV vaccine got it during weeks 24 through 36 of pregnancy. More preterm births were observed among maternal RSV vaccine recipients than among placebo recipients. However, this difference was not statistically different.

Among pregnant people in the clinical trial who received either the maternal RSV vaccine or a placebo during weeks 32 through 36 of pregnancy, preterm birth occurred in 4.2% of pregnant people who received the RSV vaccine compared to 3.7% of pregnant people who received a placebo.

Available data are insufficient to establish or exclude a causal relationship between preterm birth and RSVpreF (Abrysvo). To reduce the potential risk of preterm birth when administering maternal RSV vaccine, FDA approved the vaccine for use during weeks 32 through 36 of pregnancy. The vaccine studies did not include people who already had a higher risk of preterm births.

Other safety outcomes

Although not common in the clinical trials, hypertensive disorders of pregnancy (including pre-eclampsia) occurred in 1.8% of pregnant people who received the RSV vaccine compared to 1.4% of pregnant people who received a placebo.

Pre-eclampsia, low birth weight (meaning less than 5.5 lbs), and jaundice in newborns occurred more frequently in infants born to mothers who received the RSV vaccine compared to infants born to mothers who received a placebo. These conditions are often associated with preterm birth. 

Ongoing Studies and Surveillance

CDC and FDA will continue to monitor the safety and effectiveness of maternal RSV vaccine, review data as collected, keep the public informed of findings, and use data to make recommendations – consistent with standard practices for all vaccines.

FDA is requiring Pfizer to conduct additional studies in pregnant people. These studies are meant to look more closely at the potential  risk for preterm births and at hypertensive disorders of pregnancy  including pre-eclampsia.

CDC will monitor the safety of maternal RSV vaccination using multiple systems. The Vaccine Safety Datalink (VSD) and Vaccine Adverse Event Reporting System (VAERS) will monitor for adverse pregnancy outcomes, such as pre-term birth, and acute outcomes, such as reactogenic events. CDC’s V-safe will also be used to monitor reactions and health impacts after maternal RSV vaccination. For more information on CDC’s vaccine safety monitoring systems, see Vaccine Information and Safety Studies.

Adverse events after maternal RSV vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS), even if it is not clear that the vaccine caused the adverse event. Information on how to submit a report to VAERS is available at https://vaers.hhs.gov/index.html or by telephone at 1-800-822-7967.  Anyone can submit a report to VAERS — healthcare professionals, vaccine manufacturers, and the general public.

Storage and handling of RSVpreF vaccine (Abrysvo, Pfizer)

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.

Administering RSVpreF vaccine (Abrysvo, Pfizer)

This page provides a summary of guidance for administering RSVpreF vaccine (Abrysvo, Pfizer) for use in pregnant people, 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 people 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.

References and Resources

1. Food and Drug Administration: FDA Approves First Vaccine for Pregnant Individuals to Prevent RSV in Infants. Press Release. Silver Spring, MD: US Department of Health and Human Services, Food and Drug Administrations; 2023. https://www.fda.gov/news-events/press-announcements/fda-approves-first-vaccine-pregnant-individuals-prevent-rsv-infants
2. Food and Drug Administration. ABRYSVO package insert. Silver Springs, MD: US Department of Health and Human Services, Food and Drug Administrations; 2023. https://www.fda.gov/media/168889/download?attachment
3. Kampmann B, Madhi SA, Munjal I, et al. Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants. N Engl J Med. 2023 Apr 20; 388(1):1451–1464. doi:10.1056/NEJMoa2216480.
4. Hamid S, Winn A, Parikh R, et al. Seasonality of Respiratory Syncytial Virus – United States, 2017-2023. MMWR Morb Mortal Wkly Rep. 2023 Apr 7;72(14):355-361. doi: 10.15585/mmwr.mm7214a1
5. CDC RSV Surveillance & Research