Human papillomavirus (HPV), a sexually transmitted infection, is remarkably common, according to a recent publication from the National Center for Health Statistics, part of the Centers for Disease Control and Prevention.

The report reveals that 25 percent of men and 20 percent of women ages 18 to 59 are infected with what's called high-risk HPV—the types 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 report.

"People tend to ho-hum this whole thing, not think it’s really an issue," she says. "This is an infection that leads to cancer—it's important."

Just 15 years ago, sexually active adults had no reliable way to protect against HPV. But for young people today, the infection is preventable. The HPV vaccine, approved for girls and women in 2006 and boys and men in 2009, offers protection against the riskiest forms of the virus, ideally before they are ever exposed to it.

The CDC recommends the vaccine for all adolescents, yet most remain unvaccinated.

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 longer to discuss and they perceive parents as unsupportive of it for their kids. A consortium of National Cancer Institute-designated cancer centers released a statement (PDF) that called the low vaccination rates "a serious public health threat."

"Every parent should take stock of these statistics," says Consumer Reports' medical director, Orly Avitzur, M.D. "The vaccine provides a window of opportunity to prevent HPV-related cancers in adulthood."

HPV: A Preventable Problem

HPV is responsible for 90 percent of all cervical and anal cancers, CDC statistics show, as well as a large share of cancers of the vagina, penis, vulva, and throat. In total, HPV causes about 30,700 cancers in the U.S. each year.

According to the latest CDC recommendations, all 11- and 12-year-olds—the ages when preteens get other adolescent vaccines—should get two shots of the HPV vaccine to protect against these cancers.

Women, men who have sex with men, and a few other specific groups should get the vaccine up to age 26, the CDC says, and it's recommended for all men up to age 21. (People older than 14 will need three shots instead of two for full protection.)

For anyone older than 26, the American Cancer Society notes, the HPV vaccine is neither recommended nor approved, so it would be an off-label use. Most sexually active people will have been exposed to high-risk types of HPV by their mid-20s, and the vaccine won't protect against strains of the virus people have already been exposed to. That's why research and vaccination efforts have concentrated on younger age groups. (The vaccine is considered safe but not generally advisable for older adults based on limited data, and shots for people 26 and older aren't usually covered by insurance.)

"We really need to vaccinate our youngsters before they become sexually active," McQuillan says. That's our best hope for eventually eradicating the virus, she explains, and making sure that 20 years from now, HPV isn't as prevalent as it is today.