It has been about one month since the FDA cleared the Covid vaccine for teenagers, yet most are remaining on the sidelines. Fourteen-year old Angelina Allegrini of San Antonio got the shot, and says the key to influencing people her age lies on sites like Twitter and Instagram. There are nearly 17 million children in the country eligible to receive a coronavirus vaccine, and health experts want them protected by the start of school in the fall. They point to a rise in the highly transmissible Delta Covid variant, which is hitting children the hardest. Those who catch it are two-and-a-half times more likely to end up in the hospital.