Any illness that develops in infancy is beyond scary, especially one that’s related to breathing like RSV, or respiratory syncytial virus. But some good news on that front has just been announced that will ease lots of minds: The Food & Drug Administration (FDA) has approved the first RSV vaccine for use in pregnancy[1] that will work to protect newborn babies.

The drug, known as Abrysvo, is a vaccine given late in pregnancy to help prevent lower respiratory tract disease (LRTD) in babies from birth to 6 months caused by RSV.

In some cases, LRTD can be severe form of RSV, so the arrival of this vaccine is very welcome, notes Oluwatosin "Tosin" Goje, M.D., an OB/GYN and infectious diseases specialist at Cleveland Clinic in Cleveland, Ohio, and a member of the What to Expect Medical Review Board.

“RSV is the leading cause of infant hospitalization — and the vaccine was found to prevent severe infection and hospitalization,” says Dr. Goje.

RSV is a common contagious virus that’s passed around like a cold. Fortunately, most babies have mild symptoms for a week or two, like a fever and cough.[2]

But in those with a higher risk of severe RSV, like infants born prematurely or with a lung or heart ailment, RSV can be severe, leading to pneumonia or bronchitis.

Here’s more about the RSV vaccine, the testing it underwent and when it will be available.

What is Abrysvo, the new RSV vaccine for pregnant women?

Abrysvo is an RSV vaccine that’s just been approved for use in expectant women in order to stave off serious future respiratory illness in their infants. The vaccine has been created as a single-dose shot to be given late in pregnancy, between week 32 and week 36 of pregnancy

The trials for the vaccine were quite successful. “It’s efficacious, especially when it comes to severe lower respiratory tract disease caused by RSV,” explains Dr. Goje. The vaccine reduced the risk of severe LRTD by nearly 82 percent within three months of birth. 

And Abrysvo already has a proven track record. In May 2023, the shot, along with a second RSV vaccine, was approved for adults 60 years and older. The Centers for Disease Control and Prevention (CDC) says those in that category should speak with their doctors about getting it.

Why is an RSV vaccine during pregnancy a big deal? 

A vaccine that’s available before birth is a game changer because while the majority RSV cases are mild, there are still a great number that are far more concerning — even life-threatening.

In fact, RSV is the main cause of severe bronchiolitis in kids under 1 year old, and 2 or 3 out of 100 babies under 6 months may need hospitalization to receive oxygen to help them breathe.

Also, just last year there was a big surge in RSV cases, possibly due to the increase in masking and quarantining during 2020 and 2021. In 2022, with the advent of the COVID-19 vaccine for kids and more relaxed precautions, both young babies and older kids came down with RSV in record numbers (the RSV vaccine was still in development at that point).

By way of comparison, says infectious disease specialist and What to Expect Medical Review Board Member Rajeev Fernando, M.D., “the 2022 RSV season saw hospitalization numbers surge in the middle of November to rates of 4.9 per 100,000 from 1.1 per 100,000 at this same point in time the previous year. Hence, approval of the RSV vaccine is very timely.”

There’s also a new antibody treatment called Beyfortus (nirsevimab) that’s recommended by the CDC for infants under 8 months old who are born during or at the start of their first RSV season, which runs from October to April.

And the CDC advises that children between 9 months and 18 months of age get a dose of this treatment if they’re at a higher risk of severe RSV.

But an actual vaccine trumps a medication made from antibodies, which is why its availability is such good news. Still, says Dr. Goje, it’s not known whether this vaccine will be recommended in tandem with the antibody treatment.

“We need more CDC guidance on this topic,” she says.

Is the new RSV vaccine safe for me and my baby during pregnancy?

The short answer? Yes.

"No safety signals were detected in the mother and baby,” Dr. Goji says, meaning nothing was revealed during the clinical trials that the injection was linked to any complications in either pregnant mom or her baby.

To test for safety and effectiveness, randomized, placebo-controlled international clinical studies were performed with thousands of pregnant women — and the results were extremely positive.

In one group of 3,500 who received the vaccine, the drug lowered the risk of severe LRTD by about 82 percent within the first 90 days after birth. And in a subgroup of 1,500 pregnant women, the risk of severe illness was reduced even more effectively, by 91 percent in the first three months when compared to the placebo. By the six-month point, severe respiratory disease was down by about 77 percent. 

When will I be able to get the RSV vaccine if I’m pregnant?

The RSV vaccine is developed to be given during the third trimester (on average, the vaccines were given to the women in the clinical trial at around 30 weeks pregnant). The recommended timeframe of 32 weeks to 36 weeks pregnant for the vaccine’s use is designed, in part, to minimize side effects, adds Dr. Fernando.

As for when the RSV vaccine will be available in doctors’ offices, that schedule has not yet been determined.

“We still need more information from the CDC before some of the more practical roll-outs take place,” Dr. Goje says. 

Who should get vaccinated against RSV? 

The new RSV vaccine is approved for pregnant women during their third trimester, so speak with your doctor to find out if you’re a good candidate. As with every drug (including vaccines), there are some exceptions or certain groups of people for whom it’s not recommended.

“For this particular vaccine, the study excluded high-risk pregnancy mothers,” explains Dr. Goje. If you’re allergic to any part of the vaccine, you likely won't be able to get it, reminds Dr. Fernando. And if you’re already at risk for a premature delivery, the RSV vaccine may not be recommended to you, either, he says.

Are there any side effects related to the RSV vaccine for pregnant women?

In terms of adverse outcomes, a very low percentage who got the vaccine experienced pre-eclampsia, a hypertensive disorder, as compared with the placebo (1.8 percent vs 1.4 percent), according to the FDA. Low birth weightjaundice and premature birth were also slightly more common in those who received Abrysvo, the agency said.

But for the most part, the commonly reported side effects included: 

Thankfully, RSV usually results in mild illness in babies and children, but since it can also be much more serious, the development of a preventative vaccine is great news. Ask your doctor about the new RSV vaccine so you can find out whether you should receive it during your pregnancy. 

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