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% efficacy in preventing HPV-positive oropharyngeal cancers. 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.
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 also for boys. It is on the World Health Organization's List of Essential Medicines and prequalified vaccines. Vaccination may be cost effective in the 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 (the original Gardasil and Cervarix).
Medical uses
HPV vaccines are used to prevent HPV infection and therefore cervical cancer. Vaccinating females between the ages of nine to thirteen is typically recommended, with many countries also vaccinating males in that age range. In the United States, the CDC recommends that all 11- to 12-year-olds receive two doses of HPV vaccine, administered 6 to 12 months apart. The vaccines require three doses for those ages 15 and above. HPV vaccines are recommended in the United States for women and men who are 9–26 years of age, and are also approved for those who are 27–45 years of age.
HPV vaccination of large percentage of people within a population has been shown to decrease rates of HPV infections, with part of the benefit from herd immunity. Since the vaccines only cover some high-risk types of HPV, cervical cancer screening is recommended even after vaccination. In the U.S., the recommendation is for women to receive routine Pap smears beginning at age 21. In Australia, the national screening program has changed from the two yearly cytology (pap smears) to being based on tests for HPV DNA, based on work by Karen Canfell and others.
Efficacy
The HPV vaccine has been shown to prevent cervical dysplasia from the high-risk HPV types 16 and 18 and provide some protection against a few closely related high-risk HPV types. However, there are other high-risk HPV types that are not affected by the vaccine. The protection against HPV 16 and 18 has lasted at least eight years after vaccination for Gardasil and more than nine years for Cervarix. It is thought that booster vaccines will not be necessary.
Gardasil and Gardasil 9 protect against HPV types 6 and 11 which can cause genital warts.
Cervarix is just as effective at protecting women against persistent HPV 16 and 18 infection in the anus as it is at protecting them from these infections in the cervix. Overall, about 30 percent of cervical cancers will not be prevented by these vaccines. Also, in the case of Gardasil, ten percent of genital warts will not be prevented by the vaccine. Neither vaccine prevents other sexually transmitted diseases, nor do they treat existing HPV infection or cervical cancer.
HPV types 16, 18 and 45 contribute to 94% of cervical adenocarcinoma (cancers originating in the glandular cells of the cervix). While most cervical cancer arises in the squamous cells, adenocarcinomas make up a sizable minority of cancers. Further, Pap smears are not as effective at detecting adenocarcinomas, so where Pap screening programs are in place, a larger proportion of the remaining cancers are adenocarcinomas. Trials suggest that HPV vaccines may also reduce the incidence of adenocarcinoma.