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Gardasil, the first vaccine against the human papillomavirus (HPV), might be one of modern medicine’s big success stories. Introduced in 2006, Gardasil, and two other subsequently-released HPV vaccines (Cervarix and Gardasil 9) have slashed rates of HPV infection, which can lead to genital warts and several types of cancer. One of those is cervical cancer, which was once the leading cause of cancer death in American women. According to the Centers for Disease Control and Prevention, HPV vaccines (along with cervical cancer screening) has made it one of the most preventable cancers. First, a little background on HPV.
What is HPV?
The human papillomavirus, or HPV, is a virus that spreads through intimate skin-to-skin contact, including vaginal, oral or anal sex.
HPV is extremely common—it’s estimated that more than 9 out of 10 people will be exposed to HPV at some point in their lives (CDC, 2019-a). The CDC estimates that 79 million Americans are infected with some strain of HPV, and there are about 14 million new HPV infections each year, almost half of them in people aged 15 to 24 (CDC, 2019-b).
Which diseases does HPV cause?
HPV can cause genital warts. According to the CDC, about 1 in 100 sexually active adults have genital warts at any given time (CDC, 2017).
In women, HPV infection can cause precancerous cervical, vulvar, vaginal and anal lesions. These can lead to cancer of the cervix, vagina, and vulva. More than 9 out of 10 cases of cervical cancer are caused by HPV.
In men, HPV can cause precancerous anal lesions. It can also lead to cancer of the penis (CDC, 2019-c).
In both women and men, the virus can cause anal cancer and cancer in the back of the throat, including the base of the tongue and tonsils (oropharynx).
HPV is thought to be responsible for more than 90%of cervical and anal cancers, 70% of vaginal and vulvar cancers, 60% of penile cancers, and 60 to 70% of cancers of the oropharynx (CDC, 2019-c).
HPV and cervical cancer: understanding the link
How many strains of HPV do vaccines protect against?
HPV isn’t just one virus; it’s dozens of strains. Scientists estimate there are more than 100 overall and 40 that affect the genital area. Most HPV infections go away on their own—9 out of 10 do within two years. But certain strains of the virus can remain and cause cancer, usually many years after the initial infection (CDC, 2019-b).
Seven types of HPV cause 90% of all HPV-related cancers—HPV 16, 18, 31, 33, 45, 52, and 58. The newest HPV vaccine protects against these seven strains plus the two that cause 90% of genital warts—6 and 11. That’s nine total, hence Gardasil 9.
How have vaccines changed the HPV landscape?
According to the CDC, since the first Gardasil vaccine was introduced in 2006, infections with the HPV types that cause most HPV cancers and genital warts have dropped 86% in teen girls and 71% in young women.
Among vaccinated women, the percentage of cervical precancers caused by the HPV types most often linked to cervical cancer has dropped by 40%.
In a meta-analysis published in June 2019 in The Lancet, researchers looked at 65 studies in 14 high-income countries and found that in the years since the first HPV vaccine was introduced, there has been a “substantial” decrease in HPV infections, precancerous cervical lesions, and anogenital warts (Drolet, 2019).
The researchers said that cases of HPV types 16 and 18 — which the CDC says cause 70% of cervical cancer—decreased by 83% among girls ages 13 to 19 and by 66% among women 20 to 24.
HPV vaccines offer a chance of eradicating cervical cancer in wealthy countries within decades, one of the study’s authors added (Boseley, 2019).
The HPV vaccine: how it works and who it’s for
How common is HPV-related cancer?
Every year, nearly 200,000 U.S. women are diagnosed with cervical precancer, or abnormal cells on the cervix that have the potential to become cancer, the CDC says. Nearly 11,000 cases of cervical cancer are caused by HPV, and more than 4,000 women die from the disease.
Every year in the U.S., more than 14,000 men get cancers caused by HPV—that’s about 4 out of every 10 cases of cancer caused by HPV overall.
Who should get vaccinated?
Three HPV vaccines are available: Gardasil, Gardasil 9, and Cervarix. To find out which vaccine may be right for you, talk to your healthcare provider.
The CDC recommends that all boys and girls get two doses of the HPV vaccine at ages 11 or 12. HPV vaccination can be started at age 9.
Side effects of the vaccine are usually minor, such as soreness at the injection site.
“Studies suggest that the protection provided by HPV vaccine is long-lasting,” says the CDC. “Studies have followed people who received HPV vaccine for about 10 years, and protection has remained high in those individuals. There has been no evidence of the protection decreasing over time.”
But even women who have received HPV vaccines should get regular cervical cancer screening starting at age 21 (CDC, 2019-d).
Originally, the Gardasil vaccine was only approved for people age 26 and younger. In October 2018, the FDA approved the vaccine up through the age of 45 (FDA, 2018). In a study of 3,200 women 27 through 45 years of age, Gardasil was 88 percent effective in preventing genital warts, precancerous lesions, and cervical cancer related to HPV types covered by the vaccine, the agency said, adding that Gardasil’s efficacy in older men was inferred by the results.
HPV and pregnancy: the implications on fertility
Should I get vaccinated for HPV if I’m over 26?
The FDA hasn’t recommended that people over 26 be routinely vaccinated against HPV. Talk to your health care provider about whether the HPV vaccine is right for you.
The vast majority of Americans aged 27 to 45 have been exposed to HPV. If you’ve already been infected with a certain strain, the vaccine won’t protect against that strain. But because there are nine types of HPV, the latest vaccine could protect against any strains you haven’t been exposed to.
- Boseley, S. (2019). HPV vaccine ‘offers chance’ of wiping out cervical cancer in rich countries. Retrieved June 26, 2019 from https://www.theguardian.com/society/2019/jun/26/hpv-human-papilloma-virus-vaccine-cervical-cancer-elimination-study
- Centers for Disease Control and Prevention (CDC). (2017). Genital Hpv Infection – Cdc Fact Sheet. Genital HPV Infection – CDC Fact Sheet. Retrieved September 10, 2019 from https://www.cdc.gov/std/hpv/HPV-FS-July-2017.pdf
- Centers for Disease Control and Prevention (CDC). (2019-a). HPV Cancers. Retrieved September 10, 2019 from https://www.cdc.gov/hpv/parents/cancer.html
- Centers for Disease Control and Prevention (CDC). (2019-c). Cancers Associated with Human Papillomavirus (HPV). Retrieved September 10, 2019 from https://www.cdc.gov/cancer/hpv/basic_info/cancers.htm
- Centers for Disease Control and Prevention (CDC). (2019-d). What Should I Know About Cervical Cancer Screening? Retrieved September 10, 2019 from https://www.cdc.gov/cancer/cervical/basic_info/screening.htm
- Centers for Disease Control and Prevention (CDC). (2019-b). About HPV (Human Papillomavirus). Retrieved September 10, 2019 from https://www.cdc.gov/hpv/parents/about-hpv.html
- Drolet, M., Bénard, É., Pérez, N., & Brisson, M. (2019). Population Level-Impact and Herd Effects Following the Introduction of Human Papillomavirus Vaccination Programmes. Obstetrical & Gynecological Survey, 74(10), 590–592. doi: 10.1097/ogx.0000000000000724. Retrieved from https://www.researchgate.net/publication/336817365_Population_Level-Impact_and_Herd_Effects_Following_the_Introduction_of_Human_Papillomavirus_Vaccination_Programmes_Updated_Systematic_Review_and_Meta-analysis
- Food and Drug Administration (FDA). (2018). FDA approves expanded use of Gardasil 9 to include individuals 27 through 45 years old. Retrieved September 10, 2019 from https://www.fda.gov/news-events/press-announcements/fda-approves-expanded-use-gardasil-9-include-individuals-27-through-45-years-old
Dr. Chimene Richa is a board-certified Ophthalmologist and Senior Medical Writer/Reviewer at Ro.