As a parent, you know the danger that respiratory syncytial virus (RSV) can pose for young children. Receiving an RSV vaccine during pregnancy can help to prevent serious RSV illness in babies after they are born.
Pfizer's RSV vaccine (called ABRYSVO®) is an approved maternal vaccine that is now available in several countries around the world. When the vaccine is given during pregnancy, some of the pregnant parent's antibodies from the vaccine are passed to the baby. These antibodies help protect the baby from RSV after they are born. Right now, there are no clear rules about getting a second dose of the RSV vaccine in another pregnancy. This study is looking to see if another dose is safe to give when someone is pregnant again. Researchers also want to learn if there is any change to the number of antibodies passed to a baby after a second dose of the vaccine is given. This clinical trial will help us find out how long protection lasts from a single dose of Pfizer's maternal RSV vaccine and whether a second dose is needed during later pregnancies.