RSV Vaccine During Pregnancy
Respiratory syncytial virus, or RSV, usually causes mild cold-like symptoms, but it can cause severe illness in some people. Children under age 5, and particularly babies 6 months and younger, tend to get the sickest with RSV. Each year, thousands of young children are hospitalized because of RSV illness.
There are now two ways to prevent severe RSV illness in babies: (1) you can get a vaccine during pregnancy, or (2) your baby can get an immunization up until age 8 months. Most infants do not need both.
What is the vaccine that’s given during pregnancy?
Pregnant people can get Abrysvo, made by Pfizer, an RSV vaccine already approved for adults over 60. A single dose of this vaccine is given between 32 through 36 weeks of pregnancy during RSV season (usually September through January). It protects infants from the day they are born up to age 6 months.
How does the RSV vaccine Abrysvo work?
The vaccine causes your body to make antibodies against the virus. Antibodies are key players in the body’s immune system. They attach to cells infected with RSV and tag them for other immune cells to destroy.
When the vaccine is given during pregnancy, the antibodies made in your body cross the placenta and enter the fetal bloodstream. This process takes about 2 weeks. By the time your baby is born, they will already have antibodies to protect them against RSV. Protection lasts for 6 months.
How effective is the RSV vaccine Abyrsvo in preventing RSV in babies?
Studies show that vaccination during pregnancy:
Reduces the risk of serious RSV illness in babies up to 6 months old by 77%.
Reduces medical visits and hospitalizations due to RSV by 68%.
Are there any risks or side effects with the RSV vaccine Abyrsvo?
The most commonly reported side effects are pain at the injection site, headache, muscle pain, and nausea.
The vaccine was tested on several thousand pregnant people worldwide and found to be safe. In a few countries where it was tested, researchers noted a small increased risk of preterm birth in pregnant people who were vaccinated compared with pregnant people who weren’t vaccinated. The increase is considered so small that it could have been caused by chance or other factors, such as these countries' already higher preterm birth dates. There were no increases in preterm deaths.
What is the RSV immunization given to babies?
The RSV immunization for babies is called Beyfortus. This immunization delivers anti-RSV antibodies directly into the baby’s bloodstream. The shot is given to babies younger than 8 months who are born during or entering their first RSV season. Newborns can get the immunization even before they leave the hospital. One dose of Beyfortus has been shown to prevent severe illness due to RSV in babies up to 5 months old by 80%.
Are there any risks or side effects with the RSV immunization Beyfortus?
Minor side effects include redness and swelling at the injection site and a mild rash. No serious side effects have been reported.
Which option should I choose?
Both the vaccine given during pregnancy and the infant immunization are safe and effective ways to prevent illness caused by RSV in infants. Your healthcare professional can help you decide which option is best for you and your baby. Here is a comparison of some important facts about the Abrysvo and Beyfortus:
| Abrysvo (RSV vaccine given during pregnancy) | Beyfortus (RSV immunization given to babies) | |
|---|---|---|
| Who is it for? | Pregnant persons from 32 through 36 weeks of pregnancy during the RSV season (September through January) | • Infants up to age 8 months entering their first RSV season, AND • Infants and children aged 8 – 19 months entering their second RSV season |
| How effective is it at preventing severe RSV illness in babies? | 77% at 180 days | 80% at 150 days |
| What are the side effects? | Injection site pain, headache, muscle pain, nausea, and fever | Rash and injection site pain |
| What are the benefits? | • Your baby is born protected against RSV because the antibodies are already present. • Abrysvo may give better protection against RSV variants than Beyfortus. • It reduces the number of injections your baby gets. • There may be ongoing protection through breastfeeding. | • The antibodies in the immunization are delivered directly to the baby’s bloodstream (instead of being passed across the placenta),which may result in stronger protection. • The protection from the immunization may last longer than Abrysvo’s protection. |
Because both options are relatively new, how to pay for the vaccine or whether it will be given free by your state may not be decided yet. It is a good idea to check whether your insurance covers the option you want and whether both options are available where you live.
Also, since the RSV season may differ across the country, recommendations about when to get the vaccine or immunization may differ from state to state.
For more information, check out the following resources:
CDC: RSV Vaccination for Pregnant People
CDC: RSV in Infants and Young Children
MotherToBaby: Respiratory Syncytial Virus (RSV) Vaccine (Abrysvo)
RSV Quick Facts
Respiratory syncytial virus, or RSV, usually causes mild cold-like symptoms, but for children and babies, it can cause severe illness and in some cases hospitalization.
To prevent severe RSV illness in babies:
Pregnant people can get the Abrysvo vaccine between 32 through 36 weeks of pregnancy during RSV season.
Babies can get the Beyfortus immunization if they are younger than 8 months and entering their first RSV season or are 8-19 months entering their second RSV season.
Both vaccines are safe and effective at reducing the risk of serious illness and hospitalization due to RSV in babies.
The availability of each vaccine may be state-dependent. Talk to your healthcare provider to identify what options are available and best for you.
Glossary
Antibodies: Proteins made by the immune system in response to a foreign substance, such as a virus.
Immune System: The cells and organs that protect the body against foreign substances, such as bacteria and viruses.
Placenta: A special organ made by the body during pregnancy. It allows the transfer of nutrients, antibodies, and oxygen to the fetus from the woman. It also makes hormones that sustain the pregnancy.
References
Centers for Disease Control. RSV Surveillance & Research. Accessed 09/19/2023. https://www.cdc.gov/rsv/research/index.html
Kampmann B, Madhi SA, Munjal I, et al. Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants. N Engl J Med. Apr 20 2023;388(16):1451-1464. doi:10.1056/NEJMoa2216480.
McLaughlin JM, Khan F, Schmitt HJ, et al. Respiratory Syncytial Virus-Associated Hospitalization Rates among US Infants: A Systematic Review and Meta-Analysis. J Infect Dis. Mar 15 2022;225(6):1100-1111.
Simoes EAF, Madhi SA, Muller WJ, et al. Efficacy of nirsevimab against respiratory syncytial virus lower respiratory tract infections in preterm and term infants, and pharmacokinetic extrapolation to infants with congenital heart disease and chronic lung disease: a pooled analysis of randomised controlled trials. Lancet Child Adolesc Health. Mar 2023;7(3):180-189. doi:10.1016/S2352-4642(22)00321-2.
Last update: October 30, 2023