A young person receives an HPV vaccination.

Over the past few years, the rate of vaccination against the human papillomavirus (HPV), which helps prevent most genital warts and cervical cancers, along with some other cancers, has continued to rise steadily among adolescents.

And new research published in The Lancet has found that immunization efforts are paying off. The World Health Organization analysis of 65 studies found that in 14 countries with HPV vaccination programs—including the U.S.—the prevalence of HPV, genital warts, and cervical lesions in teen girls and women dropped significantly.

While HPV immunization efforts remain focused on adolescents, the Advisory Committee on Immunization Practices—which guides the Centers for Disease Control and Prevention on vaccines—recommended on Wednesday that men get the shot up to age 26, up from an earlier limit of age 21.

The ACIP also said that previously unvaccinated adults can consider getting the HPV vaccine up to age 45. 

Here, the rundown on why the vaccine is important, and who should get it and when. 

Who Should Get the HPV Vaccine

The CDC recommends that youngsters get two shots of the HPV vaccine at age 11 or 12, between 6 and 12 months apart. Those who are 15 or older when they begin the series need three shots within 6 months for full protection.

If your child hasn’t received the first dose at age 11 or 12, you do have some time.

It's true that it's best for people to get the HPV vaccine before they become sexually active, because it's somewhat less effective once people have been exposed to the virus. And "adolescents remain the most important focus of the HPV vaccination program in the U.S.," said the CDC in an emailed statement to Consumer Reports. 

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But in recent years,  the CDC began to recommend the vaccine for men up to age 21, women up to age 26, men who have sex with men, and a few other specific groups. 

Now, ACIP has extended that recommendation for men to age 26. It also said unvaccinated adults between age 27 and 45 can decide with their doctors whether to get the HPV vaccine. 

If you're in that latter group, you might want to discuss potential benefits and risks with your healthcare provider. According to the CDC statement, "HPV vaccine is safe for people between the ages of 9 and 45 years. In the mid-adult age range, there could be some individuals who might be able to benefit from vaccination to prevent new infections with HPV types they have not encountered before, even though the population benefit from vaccinating in this age range would be low."

Why This Vaccine Is Important

HPV, which often shows no signs or symptoms early on, is responsible for more than 90 percent of all cervical and anal cancers, CDC statistics show, and a large share of cancers of the vagina, penis, vulva, and throat. In total, HPV causes about 33,700 cancers in the U.S. each year.

And research shows that the vaccine is highly effective at preventing the development of several types of abnormal cervical cells that can progress to cervical cancer.

The new study in The Lancet, for instance, found that five to eight years after the start of a vaccination program, rates of two types of HPV most likely to cause cervical cancer dropped by 83 percent in female teens and by 66 percent in women ages 20 to 24. Researchers also found that rates of genital warts fell in teen boys and young men after the vaccination programs were put in place.

“The ability to have a vaccine that can prevent the infection that causes those cancers is such an important advancement in public health,” says Robert Bednarczyk, Ph.D., an assistant professor of global health at Emory University’s Rollins School of Public Health, who was not involved in this study. “It should be a top priority for parents to get their adolescents this vaccine.”

Vaccination Rates Are Better but Not Ideal

The most recent data from the Centers for Disease Control and Prevention shows that 66 percent of teens ages 13 to 17 have had at least their first dose of the vaccine.

That suggests vaccination rates are going up. According to a 2018 study in the Journal of Infectious Diseases, 27.4 percent of boys and men ages 9 to 26 reported receiving at least one dose in 2015 or 2016, up from just 7.8 percent a few years earlier. For girls and women, 45.7 percent had at least one dose of vaccine in 2015 or 2016.

But there’s still room for improvement: The federal government’s official goal is to have 80 percent of girls and boys ages 13 to 15 receive all necessary doses of the vaccine by 2020. 

“It’s encouraging that we are seeing an overall increase among males,” says Eshan Patel, M.P.H., a public-health researcher at the Johns Hopkins University School of Medicine and the lead author of the Journal of Infectious Diseases study. “However, overall, we’re still doing not that great.”

And rates of HPV infection in the U.S. remain high. An April 2017 report from the National Center for Health Statistics found that 25 percent of men and 20 percent of women ages 18 to 59 were infected with what's called high-risk HPV, the type that can cause cancer. Previous studies of just women put the prevalence closer to 15 percent.

"That’s pretty startling," says Geraldine McQuillan, Ph.D., an infectious-disease epidemiologist at the CDC and the lead author of the NCHS report. "People tend to ho-hum this whole thing, not think it’s really an issue. This is an infection that leads to cancer—it's important."

In addition, completing the series is a challenge for some. Research published in January in the The Journal of Infectious Diseases found that as of 2016, just 16 percent of children had finished the vaccine series by age 13, which is when the CDC recommends they complete it. And just 35 percent had finished the series by age 15.

Also of concern is that some earlier research, such as a study published in 2018 in the American Journal of Public Health, suggests that the percentage of people completing the series—at least in a timely way—may actually be dropping.

According to the American Journal of Public Health study, about two-thirds of the girls and young women who started the HPV vaccine series had completed it within a year. But by 2014, just 38 percent had done so. 

“We don't know how effective it is if you have this very delayed completion” or don’t finish the series, says that study's author, Jennifer Spencer, M.S.P.H., a Ph.D. candidate at the University of North Carolina at Chapel Hill.

Completing the Series

Research has shown that primary care physicians don't recommend the HPV vaccine as strongly as they do other vaccines for adolescents, in large part because it takes a good bit of time to discuss and they think parents don't support it for their kids. And some doctors may not consider completing the series a priority for their patients, Spencer says.

Also, doctors may not see kids this age very regularly. Adolescents may be less likely than younger children to go to a doctor for a yearly checkup.

So if your doctor doesn't bring up the HPV vaccine, ask about it.

And to make it easier for your youngster to finish the series, schedule an appointment for the second dose (or third, when needed) right after he or she gets the first, Spencer says. That way, it’s on your schedule.  

Or ask your doctor’s office staff whether they can send you a notice when it’s time for your child’s next dose. A 2016 study found that not receiving a reminder was a key reason parents forgot to take kids in to finish the HPV vaccine series.