Human Papillomavirus (HPV) Vaccination
Frequently Asked Questions: Women's Health
HPV is a virus. Like all viruses, HPV causes infection by entering cells. Once inside a cell, HPV takes control of the cell’s internal machinery and uses it to make copies of itself. These copies then infect other nearby cells. HPV infection is a slow process. In most people, the immune system clears the body of HPV before it causes disease.
HPV infections can cause genital warts. HPV infections also can cause changes in cells that can lead to cancer over time, including cancer of the cervix.
Human papillomavirus (HPV) infection is the most common sexually transmitted infection (STI) in the United States. Most people who have sex will get an HPV infection at some point in their lives.
There are about 40 types of HPV that typically infect the genitals. These HPV types are spread by skin-to-skin contact during vaginal, anal, or oral sex. You can get a genital HPV infection even if you do not have sexual intercourse.
HPV infection often has no signs or symptoms. People with HPV infection usually do not know they have it. This is one reason why HPV spreads easily.
Genital warts are growths that can appear on the outside or inside of the vagina or on the penis. Warts also can spread to nearby skin and can grow around the anus, on the vulva, or on the cervix. Warts may cause itching or pain, or they may not cause any symptoms.
Some types of HPV cause genital warts. These types are called “low-risk types” because they do not turn into cancer. Most cases of genital warts are caused by just two low-risk types of HPV: type 6 and type 11.
Warts can be removed with medication or surgery. Talk with your health care professional about treatment. Wart removers found in the pharmacy should not be used on genital warts.
The immune system fights most HPV infections and clears them from the body, usually within 2 years. But sometimes HPV infections can last longer. A longer infection with a “high-risk” HPV type can turn into cancer. It usually takes years for this to happen.
There are at least 13 types of HPV linked to cancer of the cervix, anus, vagina, penis, mouth, and throat. Most cases of HPV-related cancer are caused by just two high-risk types of HPV: type 16 and type 18.
It can take 3 to 7 years for certain changes in the cells on the cervix to become cancer. The purpose of cervical cancer screening is to detect these changes while they are still easily treated. Women with “high-grade” changes can get treatment to have the cells removed from the cervix.
Women with “low-grade” changes can be tested over time to see if the cells go back to normal.
One way to protect against HPV infection is by getting the HPV vaccine. The vaccine is safe and effective and protects against the HPV types that are the most common cause of genital warts and cancer. Millions of people around the world have gotten the HPV vaccine without serious side effects. The vaccine does not contain live viruses, so it cannot cause an HPV infection.
Vaccination works best when it is done before a person is sexually active and exposed to HPV. But vaccination can still reduce the risk of getting HPV for people who have already been sexually active. The ideal age for HPV vaccination of girls and boys is 11 or 12, but it can be given starting at age 9 and through age 26.
The HPV vaccine is given as a series of shots:
- For those aged 9 to 14, two shots of vaccine are recommended. The second shot should be given 6 to 12 months after the first one.
- For those aged 15 through 26, three shots of vaccine are recommended. The second shot should be given 1 to 2 months after the first one. The third shot should be given 6 months after the first shot.
If you are older than 26, have not been vaccinated, and are at risk of a new HPV infection, you and your health care professional can talk about whether you need the HPV vaccine. The vaccine is approved for people through age 45.
If your child has not had all of the shots, he or she does not have to start over. Your child can get the next shot that is due even if the time between them is longer than recommended. This is also true for you if you have not completed the number of recommended shots. Talk with your health care professional if you have questions about getting any shots you missed.
The most common side effect of the HPV vaccine is soreness and redness where the shot is given. There have been no reports of severe side effects or bad reactions to the vaccine.
The HPV vaccine is highly effective when given before a person has sex. The vaccine can reduce the risk of HPV-related genital warts and cancer by up to 99 percent when all recommended shots have been given. It is one of the most effective vaccines you can get.
Yes. If you have had sex, you may already be infected with one or more types of HPV. But the vaccine may still protect you against HPV types you do not have yet.
HPV vaccination helps prevent HPV infection, but it is not a cure for an HPV infection you already have. Women who have been vaccinated still need to have regular cervical cancer screening. Talk with your health care professional about when and how often you should be screened.
Cervical cancer screening includes the following:
- Pap test—A test in which cells are taken from the cervix and looked at under a microscope. This test can detect abnormal changes in cells of the cervix. If testing shows cell changes that could lead to cancer, treatment can be given before cancer develops. Women should have their first Pap test starting at age 21.
- HPV test—This test is part of cervical cancer screening for some women. It may be used along with the Pap test in women age 30 and older. This is called co-testing. The HPV test also may be used as a follow-up test for women 21 and older whose Pap tests were abnormal. The HPV test can identify most of the cancer-causing types of HPV even before there are visible changes in the cervical cells.
See Cervical Cancer Screening to learn more.
Although the HPV vaccine protects against the most common causes of genital warts and cancer, it does not protect against all HPV types. If you are sexually active, using a condom or dental dam every time you have vaginal, anal, or oral sex can help reduce the risk of HPV infection. Look for condoms and dental dams made of latex or polyurethane.
Anus: The opening of the digestive tract through which bowel movements leave the body.
Cells: The smallest units of a structure in the body. Cells are the building blocks for all parts of the body.
Cervix: The lower, narrow end of the uterus at the top of the vagina.
Dental Dam: A thin piece of latex or polyurethane used between the mouth and the vagina or anus during oral sex. Using a dental dam can reduce your risk of sexually transmitted infections (STIs).
Genitals: The sexual or reproductive organs.
Immune System: The body’s natural defense system against viruses and bacteria that cause disease.
Pap test: A test in which cells are taken from the cervix (or vagina) to look for signs of cancer.
Penis: The male sex organ.
Sexual Intercourse: The act of the penis of the male entering the vagina of the female. Also called “having sex” or “making love.”
Sexually Transmitted Infection (STI): An infection that is spread by sexual contact. Infections include chlamydia, gonorrhea, human papillomavirus (HPV), herpes, syphilis, and human immunodeficiency virus (HIV, the cause of acquired immunodeficiency syndrome [AIDS]).
Vagina: A tube-like structure surrounded by muscles. The vagina leads from the uterus to the outside of the body.
Virus: An agent that causes certain types of infections.
Vulva: The external female genital area.
If you have further questions, contact your obstetrician–gynecologist.
FAQ191. Copyright August 2020 by the American College of Obstetricians and Gynecologists
This information is designed as an educational aid to patients and sets forth current information and opinions related to women’s health. It is not intended as a statement of the standard of care, nor does it comprise all proper treatments or methods of care. It is not a substitute for a treating clinician’s independent professional judgment. Read ACOG’s complete disclaimer.