The CDC National Immunization Information Hotline TTY Service is open Monday through Friday, from 10:00 a.m. to 10:00 p.m., EST. The hotline provides information on topics such as the safety of vaccines, how many shots babies need to be protected, and policies about vaccines in the U.S. The TTY staff can answer questions about vaccine preventable diseases, refer to other useful sites and resources, and send publications about vaccine protection. The TTY staff is trained in English, Spanish and American Sign Language (ASL).