When I told my 13-year-old daughter Alice I was taking her to get a vaccine that could help prevent cancer, she was mildly intrigued. "Cool," she allowed, "but I hate shots." Luckily, she didn't put up much resistance, and so we plunged into the heart of the most heated public-health matter of the moment: vaccinating tweenage girls against a sexually transmitted virus long before (one hopes!) they become sexually active.
For me, the decision to take her wasn't difficult. Gardasil, which was approved by the FDA last June, protects against four strains of human papillomavirus (HPV). Two are believed to cause...