Human Papillomavirus Vaccine
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Human Papillomavirus Vaccine

(HPV Vaccine)

En Español (Spanish Version)

What Is Human Papillomavirus?

Human papillomaviruses (HPV) are a group of more than 100 viruses. Certain types of HPV can cause genital warts , which are growths or bumps that appear on the vulva; in or around the vagina or anus; on the cervix; and on the penis, scrotum, groin, or thigh. Some strains of HPV are associated with cervical cancer , or less commonly, cancers of the vulva, anus, or penis.

HPV is easily spread during oral, genital, or anal sex with an infected partner. About two-thirds of people who have sexual contact with a partner who has genital warts will develop them also, usually within three months of contact.

Symptoms include:

  • Fleshy, raised growths with a cauliflower shape in or around the vagina or anus; on the cervix; and on the penis, scrotum, groin, or thigh
  • Bleeding
  • Itching
  • Irritation
  • Burning
  • Secondary bacterial infection with redness, tenderness, or pus

Most people will be exposed to a form of HPV at some point in their lives, although not all will become infected or develop symptoms. Warts can appear within several weeks after sexual contact with an infected person, or they can take months to appear.

Risk factors for contracting HPV include:

  • Age: 15-30 years old
  • Multiple sexual partners
  • Having sex without condoms
  • Skin-to-skin contact with an infected partner
  • Previous history of genital warts
  • Pregnancy
  • Smoking
  • Oral contraceptives
  • Having sex at an early age

Treatment for genital warts may include topical treatments, cryosurgery (freezing), electrocautery (burning), and laser to destroy the warts. Surgical removal is sometimes recommended for large warts. An antiviral drug called alpha-interferon can be injected directly into warts that keep recurring.

What Is the HPV Vaccine?

The HPV vaccine consists of noninfectious virus-like particles that produce antibodies to prevent HPV from infecting cells. The vaccine is given by injection into the muscle and must be stored in a refrigerator prior to administration.

Gardasil, which is the vaccine currently approved by the Food and Drug Administration (FDA) protects against four types of HPV. Studies have shown that it prevented nearly 100% of precancerous cervical cell changes (HPV may lead to cervical cancer) for up to four years after vaccination.

Who Should Get Vaccinated and When?

The Centers for Disease Control and Prevention (CDC) recommends the HPV vaccine for girls 11-12 years old, and doctors can give it to girls as young as nine years old. The CDC indicates that it is important for girls to get the HPV vaccine before their first sexual contact, since the vaccine is most effective for these girls.

For girls and women 13-26 years of age who did not receive the HPV vaccine when they were younger, a "catch-up" vaccination is recommended.

The vaccine is given as a three-dose series. The first dose is given at any time, with a second dose two months after the first, and the third six months after the first. Additional doses are not recommended.

What Are the Risks Associated With the HPV Vaccine?

Although current research suggests that the HPV vaccine does not appear to cause any serious side effects, like any vaccine, it has the potential to cause serious problems, such as a severe allergic reaction.

Several mild problems have been associated with the HPV vaccine, including pain, redness, swelling, or itching at the injection site, and mild to moderate fever.

Who Should Not Get Vaccinated?

Anyone who has had a life-threatening allergic reaction to yeast or any other component of the HPV vaccine, or to a previous dose of the HPV vaccine should not get the vaccine. In addition, pregnant women should not get the vaccine since its effects in pregnant women and their unborn babies are still being studied. Finally, people who are moderately or severely ill should wait until they recover to get vaccinated.

What Other Ways Can HPV Be Prevented Besides Vaccination?

Avoiding physical contact with an infected sexual partner is the only way to completely prevent the spread of an HPV infection. Latex condoms may help reduce the spread of HPV infection and genital warts. However, condoms are not 100% effective because they cannot cover the entire genital area.

Other preventive measures include sexual abstinence, monogamous sexual relationships, regular check-ups for sexually transmitted diseases, and regular Pap smears for women starting at age 18 or at the onset of sexual activity (whichever comes earlier).

What Happens in the Event of an Outbreak?

According to the CDC, approximately 6.2 million new cases of sexually transmitted HPV infections are reported each year, and 20 million people in the United States are already infected. Since HPV vaccines cannot treat HPV infections that already exist, the best way to prevent further spread of the disease is to vaccinate women before they become infected.


National Cancer Institute

Vaccine and Immunizations
Centers for Disease Control and Prevention


Genital warts. US Centers for Disease Control and Prevention website. Available at: . Accessed February 6, 2007.

US Centers for Disease Control and Prevention website. Available at: . Accessed February 6, 2007.

US National Cancer Institute website. Available at: . Accessed February 6, 2007.

Last reviewed February 2008 by David Horn, MD, FACP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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