John Carpenter's Tales of Science Fiction: Redhead

Marnie Young is a sweet girl who wouldn't hurt a fly. But one night, without warning, she has a violent seizure. Two days later, she wakes up in a hospital room. As her vision comes into focus, she sees 17 doctors and nurses dead on the floor, blood everywhere. Soon she discovers the shocking truth: Marnie has become lethal, and everyone who comes within three feet of her dies instantly!