The human papillomavirus is the most common sexually transmitted infection, and cancers linked to it have increased significantly over the last 15 years in the United States, according to the Centers for Disease Control and Prevention. At the same time, the CDC said Thursday, HPV vaccination rates are rising — but they may not be rising fast enough.

“We are moving in the right direction, but given the fact that we have a safe and effective vaccine, there’s little reason why parents and providers aren’t vaccinating every single child,” said Ronald DePinho, a former president of MD Anderson Cancer Center.

Nearly half of adolescents ages 13 to 17 in 2017 had received all the recommended doses for HPV vaccination, while two-thirds had received the first dose. For both groups, that was a five-percentage-point increase from the previous year.

Meanwhile, 80 million Americans are infected with the virus. In the vast majority of cases, the body’s immune system clears out the infection. But in some cases, certain strains of HPV persist and can cause cervical cancer, as well as some throat, vaginal, penile and anal cancers. Throat cancer is now the most common HPV-related malignancy.

More than 43,000 people developed HPV-associated cancer in 2015, compared with about 30,000 in 1999, the CDC said. In that time frame, rates of throat cancer rose in both men and women, but more in men.

“To not take advantage of a vaccine that can prevent cancers is a lost opportunity and a tragic one,” DePinho said.

The agency said the inoculations could prevent 90 percent of HPV-caused cancer cases — those that can be directly attributed to HPV — every year. Since the vaccine’s introduction a decade ago, HPV infections and cervical precancers have fallen significantly. But it can take a long time to see the vaccine’s benefits because many cancers take several years to develop after HPV infections take hold.

The agency recommends that children ages 11 to 12 get two doses of the HPV vaccine, six to 12 months apart. Those who get the first dose after their 15th birthday should get three shots.

Outside experts welcomed the increased HPV vaccination rates but said much more improvement is needed.

Larry Copeland, a gynecologic oncologist at The James, The Ohio State University Comprehensive Cancer Center, agreed, saying it was “not satisfactory at all” that more than 50 percent of adolescents have not completed the HPV vaccine series.

“The medical community has to accept some blame here,” Copeland said, adding that some patients with HPV-related cervical cancer tell him that the vaccine wasn’t recommended by their doctors. “We have to look in the mirror. Pediatricians, primary-care doctors, come on, let’s get with the program.”

The report showed that fewer adolescents in rural areas, compared with those in urban areas, are getting the HPV vaccine as well as a recommended meningitis vaccine. And boys still lag girls in getting the HPV vaccine; about 53 percent of girls have gotten all recommended doses while 44 percent of boys have received them.

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