Respiratory syncytial virus (RSV) causes respiratory tract infections and is the most common cause of viral pneumonia in infants under age one in the U.S.

The first sign that Erin and David Harris’ daughter Emma was sick happened when she was less than 10 days old. She was lethargic, eating very little and the coughing started.

“When our youngest daughter was born, her first cries were music to our ears—but we never expected those cries to take such a scary turn,” said Erin Harris. “I was unprepared to hear our pediatrician say that Emma had RSV at 10 days old and needed to go to the ER.”

In June, Pfizer advanced a maternal immunization vaccine candidate to Phase 3 to help protect infants from contracting RSV.  

"What we’re trying to do is put the good form of a recently characterized protein—one to which people naturally form an immune response—into a vaccine in order to increase a mother’s levels of antibodies while she’s pregnant so that she can pass those antibodies to the baby before it’s born,” said Kena Swanson, Scientist, Pfizer Vaccines Research and Development. “That way, if the vaccine achieves clinical success and regulatory approval, once newborns enter the world, they can already be armed with protective antibodies to help fight against RSV.”