If you’re looking for rsv vaccine pregnancy guidance, the key choice is between vaccination during pregnancy and a long-acting antibody given to your baby. Both are designed to protect infants from severe RSV, and in most cases one option is used—not both. The right timing depends on when you’re due and where you live.
How maternal vaccination and infant antibodies differ
A maternal RSV vaccine prompts your immune system to make antibodies, which cross the placenta and give your newborn protection from birth. In the U.S., the recommended vaccine for pregnancy is Pfizer’s Abrysvo. It takes about two weeks after vaccination for protection to develop and pass to the baby.
Nirsevimab and clesrovimab are monoclonal antibodies given directly to an infant. They are not vaccines: they provide antibodies rather than prompting the baby’s immune system to make them. U.S. guidance recommends an infant antibody for babies under 8 months entering their first RSV season if the mother was not vaccinated during that pregnancy, with some exceptions. An antibody may also be considered in rare cases even when the mother was vaccinated, based on a clinician’s judgment.
The rsv vaccine pregnancy option: U.S. timing and eligibility
In most of the continental United States, the CDC recommends one dose of Abrysvo between 32 weeks, 0 days and 36 weeks, 6 days of pregnancy, during September through January. The seasonal window is intended to align protection with RSV season, which typically runs through fall and winter. Maternal antibodies protect for about the baby’s first six months, then wane.
If you are past 36 weeks and 6 days, the CDC advises against starting maternal vaccination because there may not be enough time for antibodies to develop and cross the placenta. An infant antibody is the alternative to discuss. The CDC also does not currently recommend another maternal RSV vaccine in a later pregnancy if you received one during a previous pregnancy; it recommends discussing infant antibody protection instead.
For most of the continental U.S., infant antibodies are given October through March. Babies born during that period should ideally receive a dose within their first week, often before leaving the birth hospital. Babies born from April through September who are eligible should generally receive it shortly before RSV season, such as in October or November. Local timing can differ in places with less predictable RSV patterns, including Alaska and tropical U.S. areas.
What the protection data can—and can’t—tell you
In a phase 3 clinical trial, maternal RSV vaccination reduced infants’ relative risk of RSV hospitalization by 68% in the first three months after birth and by 57% within six months. These are relative reductions, not a promise that an individual baby will avoid RSV or hospitalization. The CDC says real-world effectiveness estimates from the 2023–24 season were limited by the timing of the season and low maternal vaccine uptake.
For nirsevimab, early real-world data showed at least 70% effectiveness against infant RSV hospitalization; clinical trials also found protection against RSV-related lower respiratory illness and hospitalization. These results support both routes as ways to reduce severe disease, but they are not a direct comparison proving that one is best for every family.
Outside the U.S., check your local schedule
The dates above are U.S. CDC recommendations, not a global calendar. In the UK, EU countries and Australia, local eligibility, product access and seasonal timing need to be checked against current national guidance; recommendations can differ between countries. Ask your maternity team or baby’s clinician which product is offered where you live and when it should be given. Don’t assume the U.S. September-to-January pregnancy window applies to your location.
Questions to take to your care team
Tell your clinician your due date, whether you have received an RSV vaccine in a previous pregnancy, and where you expect to be during RSV season. Ask whether maternal vaccination or an infant antibody is recommended locally, when your baby would receive protection, and whether the dose can be arranged at the birth hospital. In the U.S., Abrysvo is the RSV vaccine recommended for pregnancy; other RSV vaccines are not approved for use during pregnancy.
As with any pregnancy decision, discuss your medical history and any concerns with your maternity clinician. Seek their guidance if you have had a severe allergic reaction to a vaccine ingredient or are unsure which product is appropriate.