RSV Immunization For Protecting Newborns

Recent approvals for new RSV immunization strategies have parents wondering whether the maternal RSV vaccine given during pregnancy or the monoclonal RSV antibody shot given at birth is right for their families.

Respiratory Syncytial Virus (RSV) is a common respiratory infection that peaks in the fall and winter months, and for some infants, it can lead to severe illness. This post provides an overview of RSV and the available immunization options so you can make informed decisions about protecting your infant.

Personal note from Dr. Ashley: Many parents in my community have had questions about these two new RSV immunizations. This information is presented to help you make an informed choice along with your healthcare provider. I support all parents regardless of vaccine choices.

What Is RSV?

RSV is a highly contagious virus that usually causes mild cold-like symptoms in healthy individuals, such as a runny nose, cough, or low-grade fever. However, for certain at-risk groups, including infants under 12 months, RSV may develop into a serious condition, like bronchiolitis or pneumonia, which may require hospital care.

How RSV Spreads

RSV spreads through:

Respiratory droplets (from coughs or sneezes)
Direct contact (e.g., handshakes or kisses)
Contaminated surfaces (e.g., toys or countertops)

Sick kids laying together on the couch. Anyone of any age can get an RSV infection, and repeat infections are possible. People are contagious for 1-2 days before symptoms appear and usually stop being contagious after symptoms disappear. An exception is infants and those with weakened immune systems who may spread RSV for up to 4 weeks after symptoms have disappeared (1,2).

The incubation period (the time between coming in contact with the virus and showing symptoms) is 2-8 days (2).

Serious RSV Outcomes

RSV is the leading cause of hospitalization in infants under 1 year old in the United States (3).

For every 1,000 infants:

0–2 months old: 24 are hospitalized (4)
3–5 months old: 13 are hospitalized (4)
6–11 months old: 8 are hospitalized (4)

Such hospitalizations can be distressing, but most infants recover within 2-4 days with appropriate hospital care (2).

Whether or not there are long term negative impacts from RSV, infection is a subject of much research. At present, the consensus is that serious RSV infections may increase the chances of wheezing but not asthma later in life (2).

The RSV related mortality rate is quite low in infants in high income countries like the United States, but unfortunately there are still RSV-related deaths every year (5). Globally, RSV is responsible for an estimated 100,000 deaths per year in children under 5 years old. 97% of these deaths occur in low and middle income countries (6).

RSV Immunization Options for Newborns

In 2023, two new immunization options for infants were approved by the FDA. The first is a vaccine given during pregnancy (Abrysvo) so that the mother produces RSV-antibodies that are passed to the child through the placenta. The second is a monoclonal antibody (Nirsevimab/Beyfortus) given after birth that directly supplies monoclonal antibodies to the child. Additionally, there is another monoclonal antibody (Palivizumab/Synagis) that has been approved for over two decades for the protection of high risk infants.

For more information, see this webpage: RSV (Respiratory Syncytial Virus) Immunizations | CDC

1. Maternal RSV Vaccine (Abrysvo – FDA Approved in 2023)

Who it’s for:

Pregnant people at 32–36 weeks gestation between the months of September – January

How it works:

Administered during pregnancy, it prompts the mother’s immune system to create RSV antibodies, which are passed to the baby via the placenta.

Protection window:

Covers the infant’s first 6 months of life, when RSV risks are highest.

Efficacy:

Reduces hospitalization risk by 68% at 3 months and 57% at 6 months.
Lowers severe RSV outcomes (e.g., ICU admission) by 82% at 3 months and 69% at 6 months.

Considerations:

Not recommended before 32 weeks or after 36 weeks and 6 days of pregnancy
Immunocompromised people may have a diminished response to the RSV vaccine
Discuss with your healthcare provider, especially if you have a high-risk pregnancy
Still in post-marketing clinical trials; early post-marketing information contributes to suspicions of increased risk of premature birth and lists other adverse events. The FDA is monitoring this closely. See the results here: Safety of RSV Vaccine among Pregnant Individuals: A Real-World Pharmacovigilance Study Using Vaccine Adverse Event Reporting System | medRxiv

2. Infant RSV Antibody Injection (Beyfortus/Nirsevimab – FDA Approved in 2023)

Who it’s for:

Infants whose mothers didn’t get maternal RSV vaccination or were vaccinated less than two weeks before giving birth
Infants born during non-peak RSV seasons
High risk children under 19 months of age entering their second RSV season

How it works:

A one-time injection provides immediate passive immunity by delivering pre-made RSV antibodies.

Protection window:

Up to 5 months of immunity.

Efficacy:

Shown to reduce RSV hospitalizations by about 70%

Considerations:

May be used as a complement to maternal vaccination (rarely) or as an alternative for infants who didn’t receive antibody protection via their mother
Still in post-marketing clinical trials
At Dr. Green Mom, we prefer Beyfortus/Nirsevimab over maternal RSV vaccination due to slightly more favorable efficacy and safety data.

3. Infant RSV Antibody Injection (Palivizumab/Synagis – FDA Approved in 1998)

Who it’s for:

High-risk infants, including those born prematurely, with chronic lung disease, congenital heart disease, or severe neuromuscular conditions if Beyfortus/Nirsevimab isn’t available
May be used in both first and second RSV seasons if needed.

How it works:

Provides passive immunity through monthly intramuscular injections during RSV season, delivering ready-made RSV antibodies

Protection window:

Short-lived and requires monthly dosing throughout RSV season (typically 5 doses)

Efficacy:

Reduces RSV-related hospitalizations by up to 55% in high-risk infants

Considerations:

Limited to infants meeting strict eligibility criteria due to high cost
Discuss with your healthcare provider if your baby falls into a high-risk category.

Timing of RSV Immunizations

The timing of RSV immunizations and the immunization that you’re offered depends on the month your infant is born in and whether you live in an area with predictable RSV patterns.* The following schedules may not apply to you; discuss with your healthcare provider.

1. Abrysvo – RSV Vaccine

Offered to people who give birth from September – January

2. Beyfortus/Nirsevimab RSV Monoclonal Antibody

Offered at birth to infants born October – March
Offered in October to infants born April – September

3. Synagis/Palivizumab RSV Monoclonal Antibody

Offered every 28-30 days during RSV season – typically November – April
Used as a second choice if Beyfortus/Nirsevimab is not available.
For high risk infants only

See this page and speak with your doctor for more information: Immunizations to Protect Infants | RSV | CDC

*Applies to most of the continental United States. Timing of administration for RSV immunization may differ in certain areas.

Other Protective Measures

Breastfeeding: Offers natural immunity, reducing RSV-related hospitalization and the need for oxygen therapy. Even partial breastfeeding provides some protection (7). Estimates of the protection offered by breastfeeding have a wide range, see this article for more details: Impact of breastfeeding on the incidence and severity of respiratory syncytial virus (RSV)-associated acute lower respiratory infections in infants: a systematic review highlighting the global relevance of primary prevention
Hygiene Practices: Wash hands frequently, clean surfaces, don’t let people hold and kiss your baby, and limit exposure to crowded places during RSV season (8).

Making an Informed Decision

RSV immunization options—maternal vaccine and infant antibodies—are tools to help parents reduce the risks of severe RSV infections. None of the RSV protection options offer 100% protection against RSV, and the majority of hospitalizations occur in otherwise healthy infants with no known risk factors. Therefore, it is important to remain vigilant about hygiene and distancing measures during RSV season regardless of underlying risk factors, breastfeeding practices, or immunization status.

Summary

RSV awareness is essential in protecting your baby’s health. Good hygiene and reducing the number of people in close contact with your infant are needed regardless of underlying risk factors or immunization status.

The RSV vaccine and monoclonal antibodies offer parents more choices for additional layers of protection. By understanding the benefits and risks of each option, you can make the best decision for your family. Speak with your healthcare provider to help determine the choice that is right for you.

Resources

We have resources that go deeper into all things vaccines to help you make informed choices for your family. Check out our popular Vaccine Strategy Guide.

For further information, you may find these links helpful:

References:

CDC. (2024). How RSV Spreads. https://www.cdc.gov/rsv/causes/index.html
Jain H, Schweitzer JW, & Justice NA. (2024). Respiratory Syncytial Virus Infection in Children. [Updated 2023 Jun 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK459215/
Suh, M., Movva, N., Jiang, X., Bylsma, L. C., Reichert, H., Fryzek, J.P., & Nelson, C.B. (2022). Respiratory Syncytial Virus Is the Leading Cause of United States Infant Hospitalizations, 2009-2019: A Study of the National (Nationwide) Inpatient Sample. The Journal of infectious diseases, 226(Suppl 2), S154–S163. https://doi.org/10.b1093/infdis/jiac120
Curns, A.T., Rha, B., Lively, J.Y., Sahni, L.C., Englund, J.A., Weinberg, G.A., Halasa, N.B., Staat, M.A., Selvarangan, R., Michaels, M., Moline, H., Zhou, Y., Perez, A., Rohlfs, C., Hickey, R., Lacombe, K., McHenry, R., Whitaker, b., Schuster, J., Pulido, C.G., Strelitz, B., Quigley, C., Weddle DNP, G., Avadhanula, V., Harrison, C.J., Stewart, L.S., Schlaudecker, E., Szilagyi, P.G., Klein, E.J., Boom, J., Williams, J.V., Langley, G., Gerber, S.I., Hall, A.J., McMorrow, M.L.. (2024). Respiratory Syncytial Virus-Associated Hospitalizations Among Children <5 Years Old: 2016 to 2020. Pediatrics March 2024; 153 (3): e2023062574. 10.1542/peds.2023-062574
Byington, C.L., Wilkes, J., Korgenski, K., & Sheng, X. (2015). Respiratory syncytial virus-associated mortality in hospitalized infants and young children. Pediatrics, 135(1), e24–e31. https://doi.org/10.1542/peds.2014-2151
Munro, A.P.S., Martinón-Torres, F., Drysdale, S.B., & Faust, S.N. (2023). The disease burden of respiratory syncytial virus in Infants. Current opinion in infectious diseases, 36(5), 379–384. https://doi.org/10.1097/QCO.0000000000000952
Mineva GM, Purtill H, Dunne CP, et al. (2023). Impact of breastfeeding on the incidence and severity of respiratory syncytial virus (RSV)-associated acute lower respiratory infections in infants: a systematic review highlighting the global relevance of primary prevention. BMJ Global Health 2023;8:e009693.
Gastaldi, A., Donà, D., Barbieri, E., Giaquinto, C., Bont, L. J., & Baraldi, E. (2021). COVID-19 Lesson for Respiratory Syncytial Virus (RSV): Hygiene Works. Children (Basel, Switzerland), 8(12), 1144. https://doi.org/10.3390/children8121144

Tags:

RSV Immunization: What Parents Should Know About Protecting Newborns

What Is RSV?

How RSV Spreads

Serious RSV Outcomes

RSV Immunization Options for Newborns

1. Maternal RSV Vaccine (Abrysvo – FDA Approved in 2023)

2. Infant RSV Antibody Injection (Beyfortus/Nirsevimab – FDA Approved in 2023)

3. Infant RSV Antibody Injection (Palivizumab/Synagis – FDA Approved in 1998)