Merck received FDA approval for Gardasil, a vaccine designed to prevent cervical cancer by blocking infection from human papillomavirus (HPV), the most common sexually transmitted disease. The vaccine targets four strains of HPV, two of which are responsible for 70% of cervical cancer cases and another two strains that cause 90% of genital warts. The FDA approved Gardasil for females ages 9 through 26, with the goal of inoculating girls before they may become sexually active. About half a ...