Rochester, Minnesota - Most cervical cancers are associated with human papillomavirus (HPV), a sexually transmitted infection. Widespread immunization with the HPV vaccine could reduce the impact of cervical cancer worldwide. Here's what you need to know about the HPV vaccine.

What does the HPV vaccine do?

Various strains of HPV spread through sexual contact and are associated with most cases of cervical cancer. Three HPV vaccines have Food and Drug Administration (FDA) approval in the U.S. — Cervarix is for girls only, while Gardasil and Gardasil 9 can be used for both girls and boys. Gardasil 9 offers girls protection against more strains of HPV that can cause cervical cancer.

All three vaccines can prevent most cases of cervical cancer if given before a girl or woman is exposed to the virus. In addition, all three vaccines can prevent vaginal and vulvar cancer in women, and Gardasil and Gardasil 9 can prevent genital warts and anal cancer in women and men.

In theory, vaccinating boys against the types of HPV associated with cervical cancer might also help protect girls from the virus by possibly decreasing transmission. Certain types of HPV have also been linked to cancers in the mouth and throat, so the HPV vaccine likely offers some protection against these cancers, too.

Who is the HPV vaccine for and when should it be given?

The Centers for Disease Control and Prevention (CDC) recommends routine HPV vaccine for girls and boys ages 11 or 12, although some organizations recommend starting the vaccine as early as age 9 or 10. It's ideal for girls and boys to receive the vaccine before they have sexual contact and are exposed to HPV because once someone is infected with the virus, the vaccine might not be as effective or might not work at all.

Research has shown that receiving the vaccine at a young age isn't linked to an earlier start of sexual activity. Also, response to the vaccine is better at younger ages than it is at older ages.

In October 2016, the CDC updated the HPV vaccine schedule to recommend that all adolescents and teens ages 9 through 14 receive two doses of HPV vaccine at least six months apart, rather than the previously recommended three-dose schedule.

Teens and young adults who begin the vaccine series later, at ages 15 through 26, should continue to receive three doses of the vaccine.

Who should not get the HPV vaccine?

The HPV vaccine isn't recommended for pregnant women or people who are moderately or severely ill. Tell your doctor if you have any severe allergies, including an allergy to yeast or latex. Also, if you've had a life-threatening allergic reaction to any component of the vaccine or to a previous dose of the vaccine, you shouldn't get the vaccine.

Does the HPV vaccine offer benefits if you're already sexually active?

Yes. Even if you already have one strain of HPV, you could still benefit from the vaccine because it can protect you from other strains that you don't yet have. However, none of the vaccines can treat an existing HPV infection. The vaccines protect you only from specific strains of HPV you haven't been exposed to already.

Does the HPV vaccine carry any health risks or side effects?

Overall, the effects are usually mild. The most common side effects of HPV vaccines include soreness, swelling or redness at the injection site.

Sometimes dizziness or fainting occurs after the injection. Remaining seated for 15 minutes after the injection can reduce the risk of fainting. In addition, headache, nausea, vomiting, fatigue or weakness also may occur.

The CDC and the FDA continue to monitor the vaccines for unusual or severe problems.

Is the HPV vaccine required for school enrollment?

The HPV vaccine is part of the routine childhood vaccines schedule. Whether or not a vaccine becomes a school enrollment requirement is decided on a state-by-state basis.

Do women who've received the HPV vaccine still need to have Pap tests?

Yes. The HPV vaccine isn't intended to replace Pap tests. Routine screening for cervical cancer through regular Pap tests beginning at age 21 remains an essential part of a woman's preventive health care.

What can you do to protect yourself from cervical cancer if you're not in the recommended vaccine age group?

HPV spreads through sexual contact — oral, vaginal or anal. To protect yourself from HPV, use a condom every time you have sex. In addition, don't smoke. Smoking raises the risk of cervical cancer.

To detect cervical cancer in the earliest stages, see your health care provider for regular Pap tests beginning at age 21. Seek prompt medical attention if you notice any signs or symptoms of cervical cancer — vaginal bleeding after sex, between periods or after menopause, pelvic pain, or pain during sex.