Human papillomavirus is the most common sexually transmitted disease in the nation, with about one in four Americans currently infected, according to the Centers for Disease Control and Prevention.

Vaccination against the potentially cancer-causing infection is increasing statewide, but Kentucky children remain among the least vaccinated in the U.S.

Dr. Rebecca Shadowen, an infectious disease specialist at The Medical Center at Bowling Green, offered a few explanations for the Bluegrass’ resistance to vaccination.

First, there is no requirement to get the HPV vaccine. The Kentucky General Assembly has introduced legislation in the past to require HPV vaccination for students entering sixth grade, but never passed a measure, according to the National Conference of State Legislatures.

Second, “there is a real problem with people who are anti-vaccine,” Shadowen said. “They’re that way, unfortunately, with outdated information. Vaccines are not linked to autism, that is very well proven.”

Third, children cannot give consent to protect themselves from the virus.

“It’s up to the parents to make that decision for them,” Shadowen said. “The reason the vaccination rate is so low has a lot to do with the misunderstanding of the risks involved for their child, and the general belief that parents feel their children will always be angels.”

Often, parents don’t understand why their 12-year-old and likely sexually inactive children need the vaccine, according to Fred Wyand, communications director at the American Sexual Health Association. But it’s important to administer the vaccine before the children become sexually active, and it works better when administered early.

“The earlier the vaccine is given, the more robust the immune response,” Wyand said.

And if children get the vaccine by age 12, the series can be completed in two doses instead of three.

In 2017, about 31.4 percent of Kentucky children aged 13 through 17 had the first dose of the HPV vaccine. In 2018, that number increased to 42 percent, according to the Kentucky Immunization Registry.

Separated by gender, girls are getting the vaccine more than boys. For the 13-17 age group, girls and boys were separated by an average of more than four percentage points for the first dose.

The percentage of children who received two or more doses dropped significantly for each age group, but that could be because administered vaccines are underreported, according to Barbara Fox, spokeswoman for the Kentucky Cabinet for Health and Family Services.

Nationwide, 66 percent of adolescents aged 13-17 had received the first dose in the vaccine series, and about half of all adolescents were up to date with the vaccine in 2017. Kentucky’s HPV vaccination rate is estimated at 39 percent or less, and rural areas reported less vaccination coverage, according to the CDC.

“I think really the vaccine is a public health marvel,” Wyand said. “The disappointing thing about it is we’re not getting it to the people who need it the most.”

There are more than 100 types of HPV. Most infections go away on their own, but some forms of HPV cause genital warts – and some types cause cancer.

Nearly 34,000 new cases of cancer are attributed to HPV annually, and almost an additional 9,000 cancers are linked to HPV, according to the CDC.

HPV affects both men and women, and causes cancers in the cervix, vagina, vulva, penis, anus, rectum and the oropharynx – the back of the tongue and throat.

More than 90 percent of both cervix and anus cancers and 70 percent of pharynx cancers are attributed to HPV. About 63 percent of penis cancers and 75 percent of vagina cancers are probably caused by HPV, according to the CDC.

People might associate HIV or other STDs with certain demographics, but HPV affects most sexually active people at some point in their lives, according to Wyand.

“HPV is incredibly common across all demographics, it really doesn’t matter,” he said.

Doctors routinely screen for cervical cancer in women, but not for other types of cancers caused by HPV. Sometimes these cancers won’t be detected until they cause health problems, according to the CDC.

“Many times, people find out about their status only after they get symptoms such as genital warts or from their Pap test result,” Fox said. “For those who will develop cancer, it often takes years if not decades.”

The HPV vaccine protects people from the most common dangerous strains, including 16 and 18 – which cause about 63 percent of all HPV-associated cancers – and 31, 33, 45, 52 and 58 – which cause an additional 10 percent, according to a 2016 CDC report.

Among the cancers caused by HPV, more than 90 percent could be prevented with the vaccine.

The cabinet recommends that parents begin vaccinating their children at around age 11 or 12.

“Early vaccination is the most optimal way to prevent HPV,” Fox said, but “many parents are reluctant to have their kids vaccinated that early.”

To increase vaccination rates, health care providers should anticipate parents’ questions and have talking points prepared to quickly educate parents. “Health care providers need to treat it like any other vaccine,” Wyand said. “It’s no different than the chicken pox vaccine.”

Education in schools could use a boost, too. “HPV prevention education should be part of the school curriculum along with other STD prevention,” Fox said in an email.

Improving public health always circles back to increasing education, according to Wyand,

“If you had a vaccine for HIV, chlamydia or syphilis, almost everyone has a cultural reference for that,” he said, “but with HPV, they’re like what is that?”