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will get human papillomavirus (HPV) within their lifetime. While many types of HPV (there are more than 200) are symptomless and go away on their own, some 

Fortunately, research shows that vaccines are effective at preventing such infections and subsequent cancers. A , which followed the country’s HPV immunization program since 2008, found no recorded cases of cervical cancer in women who were fully vaccinated against HPV at age 12–13.

Each year, about —i�Գ����ܻ徱�Բ�&�Բ�����;—are diagnosed with cancer caused by HPV, and globally  of cervical cancer cases annually are caused by the virus. But vaccination can prevent such cancers. Here’s what to know about the virus, the vaccine, and answers to common questions regarding vaccination, like misconceptions about its association with sexuality, and parental concerns regarding safety and effectiveness.

How is HPV transmitted?

HPV is spread during sexual activities, such as vaginal, anal, or oral sex. This includes intimate skin-to-skin contact, which means that HPV can be transmitted during non-penetrative sex. While condoms offer some protection, HPV can infect areas condoms don’t cover. HPV can be spread even if a person has no symptoms.

HPV commonly causes flesh-colored or whitish-gray warts that appear rough and often have a bumpy “cauliflower” look. The types of HPV that cause warts are not the same as those that cause cancer.

How does vaccination protect against HPV?

HPV vaccines work similarly to other immunizations that guard against viral infection: by stimulating the body’s immune system to produce antibodies, so that if the virus is encountered later, those antibodies will bind to it and prevent it from infecting cells.

How effective is it?

Megan Wysong, MPH, senior research associate with the International Vaccine Access Center (IVAC), says “the HPV vaccine is  at preventing persistent infections caused by HPV vaccine types.”

Since 2006, when HPV vaccines were first distributed in the U.S., the number of HPV infections and cervical precancers dropped drastically, :

• Infections with HPV types that cause most HPV cancers and genital warts have dropped 88% among teenage girls and 81% among young adult women.
• Cervical precancers caused by the HPV types most often linked to cervical cancer dropped by 40% among vaccinated women.

What vaccines are available?

All HPV vaccines protect against HPV strains that cause .

Since 2017, (9vHPV) has been the only HPV vaccine used in the U.S. It is FDA-approved and protects against nine types of HPV. 

Gardasil-4 and Cervarix are no longer used in the U.S., but they are used in other countries. In early October 2024, the .

How long does vaccination protection last?

“Research has demonstrated that HPV vaccines provide long-lasting protection against both HPV infections and diseases resulting from these infections,” says Wysong. Studies by Public Health Scotland and  “have monitored vaccinated individuals for over 10 years, revealing no indication that protection diminishes over time.”

Who should get the vaccine?

The vaccine can be given as early as age 9 and up through age 26, but Gypsyamber D’Souza, PhD ’07, MPH, MS, professor in Epidemiology, says it is most effective when given at the recommended ages of 11–12. “There is a stronger immune response when vaccinated at a young age,” she says, “and it is important to have that immune protection before exposure to HPV.” 

But kids older than 12 who have not been vaccinated can and should still be vaccinated, say both D’Souza and Wysong. While younger is ideal, the vaccine is still effective if given later. 

Children under age 15 are vaccinated with two doses, six to 12 months apart. People ages 15–26 and immunocompromised people should get three doses of the vaccine, given over a six-month period.

Are HPV vaccines linked to earlier sexual activity?

The short answer is no. Studies have shown that receiving the vaccine at the recommended age doesn’t  or cause people to become . 

This misperception is one reason parents sometimes hesitate to have their children vaccinated.

“HPV is sometimes conflated as a vaccine that is related to sexual activity, even though it is a vaccine to prevent cervical cancer,” says Rupali Limaye, PhD ’12, MPH, MA, associate professor in International Health and deputy director of IVAC. “As a result, some parents think their child does not need the vaccine if they are not engaging in sexual activity.”

Vaccines like the MMR and DTaP are more widely known and accepted because of their clear connection to preventable diseases and the reduced social stigma surrounding them, Wysong says.

Should unvaccinated adults get the HPV vaccine?

​​The CDC  that everyone under age 26 should get the HPV vaccine even if they are already sexually active, Wysong says. 

Health care providers may recommend the vaccine past 26 years of age based on health status, Limaye says. 

Although Gardasil-9 is approved for use up to age 45, it is not always recommended. “At older ages there is still some benefit to vaccination, but it is reduced since many people have already been exposed to [several types of] HPV by that age,” D’Souza says.

For older women who did not get the HPV vaccine, D’Souza says “screening can help to detect cervical precancers when they are small and treatable and prevent cancer from occurring.”

What if you already have HPV?

“The vaccine is less effective in people already exposed to HPV,” Wysong says, “but it is still recommended to get the vaccine.”

Because the HPV protects against nine strains of the virus, Limaye explains, “even if someone has been infected with one type, they can still benefit from protection against other strains.”

While the HPV vaccine prevents new HPV infections, Limaye adds, it does not treat existing HPV infections or diseases. This is why “the vaccine works best when given [at an earlier age] before someone is exposed to HPV.”

Who should not get the HPV vaccine?

Gardasil-9 is not recommended for use during pregnancy. People who are pregnant should wait to start their vaccination series until after they give birth.

Like all other vaccines, it’s not recommended to anyone who has ever had a life-threatening allergic reaction to any of its ingredients or to a previous dose of the vaccine. 

People who are ill should wait until they’ve recovered to get vaccinated for HPV.

Is the vaccine safe?

Yes. Gardasil-9 was approved after robust clinical trials with more than  Studies have consistently demonstrated its safety and have shown that it .

Side effects of the vaccine tend to be mild, if present at all. The most common side effects include soreness, swelling, or redness at the injection site.

Where can I get myself or my child vaccinated?

HPV vaccines are widely available, and most private health insurance plans cover the cost. “You can get the vaccine from a variety of sources, including your private health care provider, pharmacy, community clinics, health departments, and Planned Parenthood,” says Wysong.

If your doctor does not stock HPV vaccine, ask for a referral. “HPV vaccination is one of several adolescent vaccinations that should be routinely given to all boys and girls,” D’Souza says, but “unfortunately there are still some providers who are not routinely suggesting HPV vaccination to everyone.”

Most private health insurance plans cover the cost of HPV vaccines. Check with your insurer before going to a health care provider. 

Morgan Coulson is an editorial associate in the Office of External Affairs at the Johns ��ѻ��ý.

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