Exciting research suggests that a shot every one to three months may someday give an alternative to the daily pills that some people take now to cut their risk of getting HIV. The experimental drug has only been tested for prevention in monkeys, but it completely protected them from infection in two studies reported at an AIDS conference on Tuesday. "This is the most exciting innovation in the field of HIV prevention that I've heard recently," said Dr. Robert Grant, an AIDS expert at the Gladstone...