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Human papillomavirus (HPV) vaccines are vaccines that prevent infection by certain types of human papillomavirus (HPV). Available HPV vaccines protect against either two, four, or nine types of HPV. All HPV vaccines protect against at least HPV types 16 and 18, which cause the greatest risk of cervical cancer. It is estimated that HPV vaccines may prevent 70% of cervical cancer, 80% of anal cancer, 60% of vaginal cancer, 40% of vulvar cancer, and show more than 90% effectiveness in preventing HPV-positive oropharyngeal cancers. They also protect against penile cancer. They additionally prevent some genital warts, with the quadrivalent and nonavalent vaccines that protect against HPV types HPV-6 and HPV-11 providing greater protection. The World Health Organization (WHO) recommends HPV vaccines as part of routine vaccinations in all countries, along with other prevention measures. The vaccines require two or three doses depending on a person's age and immune status. Vaccinating girls around the ages of nine to thirteen is typically recommended. The vaccines provide protection for at least 5 to 10 years. Cervical cancer screening is still required following vaccination. Vaccinating a large portion of the population may also benefit the unvaccinated by way of herd immunity. HPV vaccines are very safe. Pain at the site of injection occurs in about 80% of people. Redness and swelling at the site and fever may also occur. No link to Guillain–Barré syndrome has been found. The first HPV vaccine became available in 2006. As of 2022, 125 countries include HPV vaccine in their routine vaccinations for girls, and 47 countries recommend them for boys, as well. The HPV vaccine is on the World Health Organization's List of Essential Medicines. Vaccination may be cost effective in low and middle-income countries. As of 2017, Gardasil 9 is the only HPV vaccine available in the United States as it provides protection against more HPV types than the earlier approved vaccines.