Human papilloma virus (HPV) vaccines may prevent infections by certain types of human papillomavirus associated with the development of cervical cancer, genital warts, and other cancers. The World Health Organization (WHO), as well as public health officials in Australia, Canada, Europe, and the United States recommend vaccination of young women against HPV. HPV vaccination is also effective in males to protect their partners from HPV infections, as well as themselves from anal cancer and genital warts, and possibly other HPV associated cancers.Two vaccines have market approval in many countries as of 2014 (called Gardasil and Cervarix in the US). Both vaccines protect against the two HPV types (HPV-16 and HPV-18) that cause 70% of cervical cancers, 80% of anal cancers, 60% of vaginal cancers, and 40% of vulvar cancers. These HPV types also cause most HPV induced oral cancers, and some other rare genital cancers. Gardasil also protects against the two HPV types (HPV-6 and HPV-11) that cause 90% of genital warts. Both vaccines have been shown to prevent precancerous lesions of the cervix. Gardasil has been shown to prevent precursors to anal, vulvar, vaginal, and penile cancers. HPV vaccines are expected to protect against HPV induced cancers of these areas as well as HPV induced oral cancers. In December 2014, the United States' Food and Drug Administration (FDA) approved a vaccine called Gardasil 9 to protect females between the ages of 9 and 26 and males between the ages of 9 and 15 against nine strains of HPV. Gardasil 9 protects against infection with the strains covered by the first generation of Gardasil (HPV-6, HPV-11, HPV-16, and HPV-18) and protects against five other HPV strains responsible for 20% of cervical cancers (HPV-31, HPV-33, HPV-45, HPV-52, and HPV-58).Worldwide, HPV is the most common sexually transmitted infection in adults. For example, more than 80% of American women will have contracted at least one strain of HPV by age fifty. Although most women infected with genital HPV will not have complications from the virus, worldwide there are an estimated 529,000 new cases of cervical cancer and 275,000 deaths per year. About 85 percent of cancers, and 80% of deaths from cervical cancer occur in developing countries. In the United States, most of the approximately 11,000 cervical cancers found annually occur in women who have never had a Pap smear, or did not follow up on abnormal Pap smear results. HPV is also the cause of cervical intraepithelial neoplasia (CIN). CIN is a precursor to cervical cancer, and is painful and costly to treat. It is not known how many women worldwide are diagnosed with CIN.Since the vaccine only covers some high-risk types of HPV, experts still recommend that women get Pap smear screenings even after vaccination. In the US, the recommendation is for women to receive routine Pap smears beginning at age 21. Additional vaccine candidate research is occurring for next generation products to extend protection against additional HPV types.