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 and other cancers caused by HPV 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. Gardasil 9 is an HPV vaccine approved by the US Food and Drug Administration (FDA) and can be used for both girls and boys.

This vaccine can prevent most cases of cervical cancer if the vaccine is given before girls or women are exposed to the virus. This vaccine can also prevent vaginal and vulvar cancer. In addition, the vaccine can prevent genital warts, anal cancers, and mouth, throat, head and neck cancers 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.

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

The Centers for Disease Control and Prevention (CDC) recommends that the HPV vaccine be given to girls and boys between ages 11 and 12. It can be given as early as age nine. It’s ideal for girls and boys to receive the vaccine before they have sexual contact and are exposed to HPV. Research has shown that receiving the vaccine at a young age isn’t linked to an earlier start of sexual activity.

Once someone is infected with HPV, the vaccine might not be as effective. Also, response to the vaccine is better at younger ages than it is at older ages.

The CDC recommends that all 11 and 12 year olds receive two doses of HPV vaccine at least six months apart. Younger adolescents ages 9 and 10 and teens ages 13 and 14 also can receive vaccination on the two-dose schedule. Research has shown that the two-dose schedule is effective for children under 15.

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

The CDC recommends catch-up HPV vaccinations for all people through age 26 who aren’t adequately vaccinated.

The US FDA recently approved the use of Gardasil 9 for males and females ages 9 to 45. If you’re age 27 to 45, discuss with your doctor whether he or she recommends that you get the HPV 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?

The HPV vaccine has been found to be safe in many studies.

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. Headaches, nausea, vomiting, fatigue or weakness also may occur.

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

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 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 doctor 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.

This article was first published on Mayo Clinic and can be accessed at https://www.mayoclinic.org/diseases-conditions/hpv-infection/in-depth/hpv-vaccine/art-20047292