Maternal Respiratory Syncytial Virus Vaccination (2024)

Summary of Key Recommendations and Points

  • The American College of Obstetricians and Gynecologists (ACOG) recommends a single dose of Pfizer’s RSV vaccine (Abrysvo) for eligible pregnant individuals between 32 0/7 and 36 6/7 weeks of gestation who do not have a planned delivery within 2 weeks, using seasonal administration, to prevent RSV lower respiratory tract infection (LRTI) in infants.
  • In most of the continental United States, pregnant patients are eligible to receive the maternal RSV vaccine from September 2024 through January 2025. Those eligible for the maternal RSV vaccine are those who did not receive the maternal RSV vaccine during the 2023–2024 season and who are not planning to have their infant receive the monoclonal antibody nirsevimab.
  • Administration of the RSV vaccine can vary in jurisdictions outside of the continental United States. In jurisdictions where RSV seasonality differs from most of the United States, CDC recommends that health care professionals follow state, local, or territorial guidance for timing administration of the RSV vaccine.
  • It is currently not recommended that pregnant patients who received the maternal RSV vaccine during the 2023–2024 RSV season receive an additional dose during a subsequent pregnancy. For patients vaccinated in a previous pregnancy, their infants should receive nirsevimab during the 2024–2025 respiratory season.
  • Clinicians should counsel patients about the maternal RSV vaccine and the monoclonal antibody nirsevimab as safe and effective ways to prevent severe LRTI caused by RSV in infants.
  • Patient preferences should be considered when determining whether to administer the maternal RSV vaccine or not to administer the maternal RSV vaccine and opt for administration of nirsevimab to the infant after birth.
  • For the 2024–2025 respiratory season, there is no anticipated supply limitation of the maternal RSV vaccine for pregnant people. Supply of nirsevimab could be limited early in the season, but it is anticipated that there will be no limitations after October 2024. This limited supply of nirsevimab could be a key component of conversations and decision making with patients regarding maternal vaccination. Maternal vaccination should be encouraged, particularly in areas where the monoclonal antibody is unavailable.
  • It is critically important that pregnant patients receive all recommended vaccines. Maternal RSV vaccine can be safely administered at the same time as other vaccines routinely recommended during pregnancy.
  • It is important that clinicians document receipt or declination of maternal RSV vaccination in the patient’s medical chart.
  • The only RSV vaccine approved for use during pregnancy is Pfizer’s bivalent RSVpreF vaccine, Abrysvo.
  • The following vaccines are not approved for use in pregnancy: GSK’s RSV vaccine, Arexvy, and Moderna’s RSV vaccine, MRESVIA.
  • Pregnant patients who receive the RSV vaccine during pregnancy should be encouraged to participate in V-safe.

Background

Respiratory syncytial virus is a common respiratory virus that usually causes upper respiratory illness, but RSV can be a serious lower respiratory tract illness for some groups, including infants and older adults. Currently, there is no antiviral treatment for severe RSV disease except for highly immunocompromised patients, and there is no licensed pediatric vaccine.

Respiratory syncytial virus is one of the most common causes of childhood respiratory illness and results in annual outbreaks of respiratory illnesses in all age groups. An estimated 58,000–80,000 children under age 5 years are hospitalized each year nationwide because of RSV infection, with some requiring oxygen, intravenous fluids, or mechanical ventilation. The hospitalization rate is highest among infants 0–6 months of age 1 . Each year, an estimated 100–300 children younger than age 5 years, particularly if under age 6 months, die because of RSV in the United States 2 . Furthermore, RSV disease in early life has been associated with complications such as secondary bacterial infections, inappropriate use of antibiotics, and long-term respiratory illness, including asthma.

RSV Prevention: Maternal Vaccination

On August 21, 2023, the FDA approved the first RSV vaccine, Abrysvo, for use in pregnant individuals to protect newborns and infants against severe RSV disease in the first 6 months after birth. The unadjuvanted bivalent (RSV A and B) pre-F protein-based vaccine was approved by the FDA to be administered as a single dose between 32 0/7 and 36 6/7 weeks of gestation 3 .

On September 22, 2023, the CDC’s Advisory Committee on Immunization Practices (ACIP) voted to recommend a single dose of maternal RSV vaccination for pregnant people at 32 0/7 through 36 6/7 weeks of gestation, using seasonal administration, to prevent RSV LRTI in infants 4 .

Importantly, while there are RSV vaccines from GSK and Moderna approved for use in older adults, these are not approved for use in pregnancy. Currently, the only RSV vaccine approved for use in pregnancy is Pfizer’s bivalent RSVpreF vaccine, Abrysvo.

Vaccine Efficacy

Among approximately 3,500 pregnant individuals who received Abrysvo, compared to approximately 3,500 pregnant individuals who received placebo, Abrysvo reduced the risk of severe LRTI in infants by 81.8% within 90 days after birth, and 69.4% within 180 days after birth. Additionally, in a subgroup of pregnant individuals who were at 32 through 36 weeks of gestation, of whom approximately 1,500 received Abrysvo and 1,500 received placebo, Abrysvo reduced the risk of severe LRTI by 91.1% within 90 days after birth when compared to placebo. Within 180 days after birth, Abrysvo reduced the risk of LRTI by 57.3% and by 76.5% for severe LRTI, when compared to placebo 3 . There are no post-authorization real-world data on the effectiveness of the vaccine yet.

Vaccine Safety

In Fall 2023, V-safe was expanded to include the maternal RSV vaccine, and as with other vaccines, the side effects most commonly reported in V-safe by pregnant individuals who received the RSV vaccine were pain at the injection site, headache, muscle pain, and nausea 3 . These reports are consistent with pre-licensure studies ( 5 , ACIP Meeting Slides).

The prescribing information for Abrysvo includes a warning to inform patients that a numerical imbalance in preterm births in Abrysvo recipients (5.7%) occurred compared to those who received placebo (4.7%)). This imbalance was only seen in trial participants residing in low- to middle-income countries with no temporal association to vaccination or association with other adverse events in the mother or the newborn. Thus, the available data are insufficient to establish or exclude a causal relationship between preterm birth and Abrysvo. The U.S. Food and Drug Administration (FDA) warning informs health care professionals that to mitigate the theoretical risk of preterm birth following administration of RSV vaccine before 32 weeks of gestation, Abrysvo should be administered as indicated in eligible pregnant individuals at 32 through 36 weeks of gestation 2 . Findings of safety surveillance in the Vaccine Safety Datalink (VSD) observed that the incidence of preterm births was 4.1% among pregnant persons who received Abrysvo during the 2023–2024 respiratory season ( 5 , ACIP Meeting Slides). This rate is within the expected range of the incidence of preterm births (3.1–6.1%) before introduction of this vaccine. Among reports received in the Vaccine Adverse Event Reporting System (VAERS), the most frequent adverse events reported were pregnancy-specific conditions (eg, preterm delivery) after the maternal Pfizer RSV vaccine. These reports are as expected for a vaccine recommended at 32–36 weeks of gestation. These findings are also consistent with a retrospective observational cohort study of pregnant individuals who delivered at 32 weeks of gestation or later and found that the RSVpreF vaccine was not associated with an increased risk of preterm birth and perinatal outcomes 6 .

The Centers for Disease Control and Prevention and FDA will continue to monitor maternal RSV vaccine safety in VAERS, V-safe, and VSD.

Pregnant patients who receive the RSV vaccine during pregnancy should be encouraged to participate in V-safe. For more information and to register for V-safe, patients can visit the CDC website.

RSV Prevention: Monoclonal Antibody Products

On August 3, 2023, CDC recommended the use of nirsevimab, a long-acting monoclonal antibody, for the prevention of RSV in infants and some young children at high risk for complications from RSV. The Centers for Disease Control and Prevention recommends one dose of nirsevimab for all infants younger than 8 months, born during—or entering—their first RSV season. The optimal timing for administration is at birth or within the first week of birth when infants are born during the RSV season. Infants younger than age 8 months who do not receive the monoclonal antibody at birth can receive it, regardless of gestational age at birth or the presence of underlying medical conditions. The Centers for Disease Control and Prevention also recommends that infants born to patients who were previously vaccinated with the maternal RSV vaccine during the 2023–2024 RSV season, receive nirsevimab. Some exceptions include when infants are born less than 14 days after maternal vaccination, when there is any concern that the maternal immune response to the vaccine will be inadequate, or when there is any condition that could affect the transplacental transfer of antibodies.

For some children between the ages of 8 and 19 months who are at increased risk of severe RSV disease, such as children who are severely immunocompromised, a dose of nirsevimab is recommended in their second season 2 . For more information on the use of nirsevimab, see CDC’s MMWR.

Nirsevimab was effective against RSV-associated hospitalization among infants in their first RSV season during the 2023–2024 RSV season by 91% as reported in NSVN (New Vaccine Surveillance Network) and 98% in VISION (Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network) ( 7 , ACIP Meeting Slides).

Another monoclonal antibody product, palivizumab, remains available and recommended by the American Academy of Pediatrics (AAP) for preterm infants born at less than 29 weeks of gestation and some infants under age 24 months at increased risk of hospitalization for RSV infection 8 . For more information on palivizumab, see AAP’s Policy Statement.

ACOG Recommendations

The American College of Obstetricians and Gynecologists recommends a single dose of Pfizer’s RSV vaccine (Abrysvo) for eligible pregnant individuals between 32 0/7 and 36 6/7 weeks of gestation who do not have a planned delivery within 2 weeks, using seasonal administration, to prevent RSV LRTI in infants. Pregnant individuals who did not receive the maternal RSV vaccine during the 2023–2024 RSV season are eligible to receive the maternal vaccine this 2024–2025 respiratory season.

For most of the continental United States, RSV season occurs from September through March. Respiratory syncytial virus vaccination is recommended for eligible pregnant individuals during the months of September through January. In jurisdictions with seasonality that differs from most of the continental United States (eg, Alaska, jurisdictions with tropical climates), health care professionals should follow state, local, or territorial guidance on the timing of administration 4 .

It is not recommended that pregnant patients who received the maternal RSV vaccine during the 2023–2024 RSV season receive an additional dose during a subsequent pregnancy. However, their infants should receive nirsevimab during the 2024–2025 respiratory season.

Most newborns and infants will not need both maternal vaccination and monoclonal antibody administration. However, because the earliest time of vaccination is 32 0/7 weeks, and at least 14 days are needed from the time of maternal vaccination for development and transplacental transfer of maternal antibodies to protect the infant, infants born at less than 14 days after receiving the vaccine should receive nirsevimab regardless of maternal vaccination status 4 .

Adding a new vaccine to the maternal immunization platform does not come without several implementation considerations. The American College of Obstetricians and Gynecologists encourages obstetrician–gynecologists to work with their staff and administrators to develop an implementation strategy that ensures patients have access to all recommended maternal vaccines.

For immunization resources and additional clinical guidance, please visit Physician Tools for Immunizationpage.

Counseling

All infants are recommended to be protected from severe RSV disease by either the maternal RSV vaccine or nirsevimab for the 2024–2025 RSV season. Both are safe and effective interventions available for RSV prevention in infants this season, and the CDC has not recommended a preferred approach.

Pregnant patients should be counseled about RSV and the risk of infection to their newborns and young infants. Clinicians should explain the difference between RSV, influenza, and COVID-19, and the need for different vaccines to protect against each of these infections.

Clinicians should counsel patients about the benefits of maternal RSV vaccination as a safe and effective way to prevent severe LRTI caused by RSV in infants through age 6 months.

Clinicians should also counsel patients regarding the monoclonal antibody nirsevimab as a safe and effective option for newborns if the maternal RSV vaccine is not received during pregnancy or if the patient was previously vaccinated during pregnancy. If there is a limited supply of nirsevimab at any point during the season, discussions concerning the benefit of maternal vaccination should occur.

Patient preferences should be considered when determining whether to administer the maternal RSV vaccine or not to administer the maternal RSV vaccine and rely on administration of nirsevimab to the infant after birth. Unvaccinated patients should be made aware that if they plan to have their newborn receive nirsevimab, they do not need to receive the maternal RSV vaccine during pregnancy.

See Box 1 for additional counseling support for clinicians.

Box 1.

Counseling Guide for Clinicians

Maternal RSV Vaccine Benefits and Considerations

  • Provides immediate protection at birth and for the first 6 months of life when maternal vaccination occurs at least 14 days before birth

  • Reduces the number of vaccines the infant receives at birth

  • Requires administration at 32 0/7 to 36 6/7 weeks of gestation

  • Can be given with other vaccines in pregnancy

  • Must be documented in maternal medical record and delivery record to inform decision making for infant

Monoclonal Antibody Benefits and Considerations

  • Results in antibody delivery directly to the newborn versus passive transfer from maternal vaccination

  • Is highly neutralizing to RSV site 0 of the RSV preF protein

  • Is more susceptible to the development of resistance through mutations of RSV Pre-F

  • Results in substantial protection for up to 150 days after administration

  • Ideally should be administered at birth or within the first week after delivery during the RSV season

  • Can be given to newborns and infants whose mothers did not receive RSV vaccine, delivered less than 14 days after vaccination, or have underlying conditions that result in inadequate maternal immune responses to vaccination or transplacental antibody transfer

Coadministration with Other Maternal Vaccines

It is critically important that pregnant patients receive all recommended vaccines. Maternal RSV vaccine can be administered at the same time as other vaccines routinely recommended during pregnancy 4 .

It is recommended that clinicians discuss all vaccines recommended during pregnancy (COVID-19, influenza, Tdap, RSV) with their patient at their first prenatal encounter to plan for when patients are eligible to receive them and to reduce vaccine burden.

Documentation

Documentation of vaccine receipt or declination is an essential component of any immunization program. All vaccines received or declined should be documented in the patient’s chart and state immunization information system. As such, clinicians should document receipt or declination of maternal RSV vaccination in the patient’s medical chart. Documentation of RSV vaccination or declination is especially critical because of the relationship between maternal RSV vaccination and infant monoclonal antibody administration. Hospitals and pediatric care professionals will need to know the maternal RSV vaccination status to counsel patients appropriately about the monoclonal antibody for the newborn.

For more information on documentation and coding, please visit Immunization Coding for Obstetrician–Gynecologists.

Please contact [emailprotected] with any questions.

Maternal Respiratory Syncytial Virus Vaccination (2024)
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