The human papillomavirus (HPV) is the most common sexually transmitted infection worldwide. In the United States, more than six million people are infected each year. Although most HPV infections are benign, two strains of HPV cause 70 percent of cervical cancer cases. Two other strains of HPV are associated with 90 percent of genital warts cases.
In June 2006, the Food and Drug Administration (FDA) approved the first vaccine against HPV. Sold as Gardasil, the quadrivalent vaccine is intended to prevent four strains of HPV associated with cervical cancer, precancerous genital lesions, and genital warts. Following FDA approval, the national Advisory Committee on Immunization Practices (ACIP) recommended routine vaccination for girls ages 11-12 with three doses of quadrivalent HPV vaccine. Thereafter, state legislatures around the country engaged in an intense effort to pass laws mandating vaccination of young girls against HPV. This activity was spurred in part by an intense lobbying campaign by Merck, the manufacturer of the vaccine.