The HPV Vaccine and the Risk of Cervical Cancer
Human papillomavirus (HPV) is a virus that causes cervical cancer and genital warts. Persistent infection with certain types of HPV can lead to cancer, the most common being of the cervix, which affects more than 10,000 American women every year. Two vaccines (Gardasil and Cervarix) are available to prevent infection with the types of HPV known to cause cervical cancer. It is hoped that these vaccines will significantly reduce the occurrence of cervical cancer.
HPV is spread by skin-to-skin contact, including sexual intercourse, oral sex, anal sex, or other genital or hand to genital contact. People do not become infected with HPV by touching an object, such as a toilet seat. Condoms do not provide complete protection from HPV infection and up to 80 percent of sexually active adults will acquire HPV infection before the age of 50. A majority of women and men first become infected with HPV between ages 15 and 25 years. Most people who are infected with HPV have no signs or symptoms and clear the infection within two years, often without treatment. However, in 10 to 20 percent of women, the infection persists and may result in a greater chance of developing cervical cancer. Because it usually takes at least 20 years for HPV infection to cause cervical cancer, regular testing is important to detect abnormalities early, before cancer develops.
There are over 40 different types of HPV that affect women or men. Researchers have labeled these HPV types as being high or low risk for causing cervical cancer.
- HPV types 6 and 11 can cause about 90 percent of genital warts. These types are low- risk because they do not cause cervical cancer.
- Types 16 and 18 are high-risk types that cause about 70 percent of cervical cancer. HPV types 45 and 31 are also high-risk types, causing about 5 to 10 percent of cervical cancers.
There are two HPV vaccines available:
- (Gardasil) helps to prevent infection with four HPV types (6, 11, 16, and 18)
- (Cervarix) prevents infection with HPV types 16 and 18, and it may offer some protection against HPV types 45 and 31.
Gardasil is given by injection and requires three doses. The first injection is followed by a second and third dose two and six months later, respectively.
Cervarix is also given by injection and requires three doses, although the schedule is slightly different than with Gardasil; the first injection is followed by a second and third dose one and six months later, respectively.
In the United States, HPV vaccination is recommended for girls and women between ages 9 and 26 years. Vaccination with Gardasil is recommended for boys and men between ages 9 and 21 years and can be given up to age 26. With both vaccines, you gain the greatest protection from HPV when vaccinated BEFORE becoming sexually active. However, if you are under 26 years old and have been sexually active, had genital warts, a positive HPV test, or an abnormal Pap smear, you may still obtain some benefit from the HPV vaccine.
The HPV vaccine may cause mild redness, tenderness, or swelling near the injection site. There may be a risk of feeling faint, dizziness or fatigue. These symptoms are mild and usually go away quickly. There are no known long-term side effects of the HPV vaccine. The vaccine is not currently recommended during pregnancy.
The HPV vaccine is not perfectly protective and some women will acquire an HPV infection despite having being vaccinated. The vaccine does not treat pre-existing infections and other types of high-risk HPV or prevent other sexually transmitted infections (STIs), including human immunodeficiency virus (HIV), herpes, chlamydia, and gonorrhea. It is important to practice safe sex, including the use of a condom, to reduce the risk of all STIs. If you are 26 years or younger, the HPV vaccination may help protect you from infection. Regular Pap smears, recommended to start at age 21 and follow up tests that your health care provider recommends are the best ways to prevent cervical cancer and other STIs.
Dr. Stacey Hunt-Okolo