Why the RSV Vaccine Is Recommended During Pregnancy

Respiratory syncytial virus (RSV) is one of the leading causes of lower respiratory infections in infants, and severe cases can lead to hospitalization. But you can help protect your newborn against RSV before they’re even born — by getting the maternal RSV vaccine.

Ob/Gyn Oluwatosin Goje, MD, who specializes in infectious diseases, explains how the vaccine can help, when to get it and what side effects it may bring.

Types of RSV vaccines

Right now, there’s only one type of RSV vaccine recommended in pregnancy, Abrysvo™.

“Receiving the maternal RSV vaccine during pregnancy allows your body to develop antibodies that then transfer to the fetus,” Dr. Goje explains. “After birth, this protects your baby while they’re too young to receive their own vaccines.”

That’s especially important because the most severe cases of RSV happen early in infancy, before their bodies can fight it off on their own.

Babies under 1 year old (especially those under 6 months) are more likely than older children to be hospitalized for RSV. The risk is even higher for those who:

• Were born preterm
• Have chronic heart or lung disease
• Have a weakened immune system

But the maternal RSV vaccine has been shown to reduce the chances of severe RSV in babies. One study found that the maternal RSV vaccine reduced severe illness by nearly 82% in the first three months after birth, and by about 69% in the first six months.

In other words: “We know this vaccine works,” Dr. Goje emphasizes.

RSV vaccination recommendations during pregnancy

RSV is a seasonal illness that ramps up in the fall and winter. So, the maternal RSV vaccine is typically offered if you’re expected to give birth during high-risk months.

Here’s a look at the current vaccine guidelines:

• Time of year: The vaccine is offered September 1 through January 31, which is considered “respiratory virus season” in the U.S.
• Stage of pregnancy: You’re eligible to receive the RSV vaccine late in your third trimester, between weeks 32 and 36.

Those guidelines raise an obvious question: What if you reach weeks 32 to 36 outside that strict window of time?

Dr. Goje says babies born outside the RSV vaccine window should receive a preventive RSV injection (called nirsevimab) once respiratory virus season approaches.

“The RSV injection isn’t a vaccine. It’s a long-acting monoclonal antibody that helps protect babies during the time when RSV tends to be most severe,” she explains. “Those monoclonal antibodies can be given to infants up to eight months old.”

Possible side effects of the RSV vaccine

RSV vaccine side effects during pregnancy tend to look the same as those from many other vaccines. They may include:

• Sore arm
• Low fever
• Pain, redness or swelling where the shot was given
• Fatigue
• Headache
• Muscle aches

These symptoms are usually short-lived and go away on their own within a few days.

Other considerations

If you don’t get the RSV vaccine during your pregnancy, your baby can still be protected from the virus. Your child’s provider will recommend that they get a protective RSV immunization soon after birth. Again, this isn’t a vaccine; it’s a dose of protective antibodies.

There are a couple other points worth calling out, too:

• It’s a one-time vaccine. At this time, the recommendation is that you receive the RSV vaccine during only one pregnancy. “If you received the maternal RSV vaccine during a past pregnancy, the recommendation is that your baby be eligible to receive monoclonal antibodies, preferably at birth or within the first week of life,” Dr. Goje explains.
• It takes two weeks to start working. After you get the RSV vaccine, it takes your body at least two weeks to start transferring antibodies to the fetus. In the case of a preterm birth, your baby should be given monoclonal antibodies.

Speak with your healthcare provider to better understand your options and decide what’s best for you.

Final thoughts

Infants are at especially high risk of severe RSV — but getting the vaccine during pregnancy is one of the most effective ways to help protect your child from it.

“Severe cases of RSV can affect healthy, full-term babies who don’t have any risk factors,” Dr. Goje cautions. “So, prevention strategies focus on keeping them safe during their first months of life, when they’re most vulnerable to the virus.”