The Food and Drug Administration announced Monday that it had approved a vaccine administered to mothers late in their pregnancies to protect their babies from RSV, or respiratory syncytial virus. The single-dose shot, made by Pfizer, is the first vaccine that protects infants from RSV, and uses maternal immunization to inoculate them through their first six months of life. It is the second treatment approved by the FDA to prevent RSV in infants, after the agency signed off on an injectable drug last month that circulates antibodies through the bloodstream. Alejandra Gurtman, Pfizer’s senior vice president of clinical research and development for vaccines, told CNBC on Monday that the company hopes the new shot, called Abrysvo, will be on shelves by November. “When you think globally, this vaccine could potentially have a huge public health impact,” she said. “After 50 years of trying to find a way where we can protect babies during the first three or especially six months of life, this vaccine is something I’m very proud of.”