Gardasil is an HPV vaccine for use in the prevention of certain strains of human papillomavirus (HPV). It was developed by Merck & Co. High-risk human papilloma virus (hr-HPV) genital infection is the most common sexually transmitted infection among women. The HPV strains that Gardasil protects against are sexually transmitted, specifically HPV types 6, 11, 16 and 18. HPV types 16 and 18 cause an estimated 70% of cervical cancers, and are responsible for most HPV-induced anal, vulvar, vaginal, and penile cancer cases. HPV types 6 and 11 cause an estimated 90% of genital warts cases. HPV type 16 is responsible for almost 90% of HPV-positive oropharyngeal cancers, and the prevalence is higher in males than females. Though Gardasil does not treat existing infection, vaccination is still recommended for HPV-positive individuals, as it may protect against one or more different strains of the disease. The vaccine was approved for medical use in the United States in 2006, initially for use in females aged 9–26. In 2007, the Advisory Committee on Immunization Practices (ACIP) recommended Gardasil for routine vaccination of girls aged 11 and 12 years. As of August 2009, vaccination was recommended for both males and females before adolescence and the beginning of potential sexual activity. By 2011, the vaccine had been approved in 120 other countries. In 2014, the US Food and Drug Administration (FDA) approved a nine-valent version, Gardasil 9, to protect against infection with the strains covered by the first generation of Gardasil as well as five other HPV strains responsible for 20% of cervical cancers (types 31, 33, 45, 52, and 58). In 2018, the FDA approved expanded use of Gardasil 9 for individuals 27 to 45 years old. Types Gardasil is available as Gardasil which protects against 4-types of HPV (6, 11, 16, 18) and Gardasil 9 which protects against an additional 5-types (31, 33, 45, 52, 58). Medical uses In the United States, Gardasil is indicated for: girls and women 9 through 45 years of age for the prevention of the following diseases: Cervical, vulvar, vaginal, anal, oropharyngeal and other head and neck cancers caused by Human Papillomavirus (HPV) types 16, 18, 31, 33, 45, 52, and 58. Genital warts (condyloma acuminata) caused by HPV types 6 and 11. girls and women 9 through 45 years of age for the following precancerous or dysplastic lesions caused by HPV types 6, 11, 16, 18, 31,