Among teenage girls in the United States, cases of the human papillomavirus (HPV) have been slashed by almost two-thirds thanks to a vaccine developed a decade earlier. Immunization rates, however, remain low – only around 40 percent of those ages 13 to 17 get the shot.

What accounts for this poor popularity of the HPV vaccine?

The Gardasil vaccine works against four HPV strains, which cause all cases of cervical cancer. The virus, though, is also a scourge causing genital warts and cancers of the mouth, throat and anus.

Most parents are believed to take a pass on the vaccine due to fears of it being a license for increased sexual activity.

Pediatrician Dr. Alix Casler of Orlando Health Physicians Associates said this does not make sense, as the goal is to immunize kids when there is not any risk of exposure yet.

"There's an extreme amount of data that shows educating our children does the exact opposite," she revealed in an interview, pertaining to parental fears of the vaccine pushing kids toward risky sexual behavior.

Together with two dozen other pediatricians, Casler launched an initiative in 2013 to promote HPV immunization across the country, writing and speaking extensively about the topic.

And sex education could be key to alleviating these fears. According to the U.S. Department of Health and Human Services, 87 percent of teens in a 2012 survey saying it would be “much easier” to delay sexual activity and avoid getting pregnant if they only have open conversations with their parents about sex.

The New York Times echoed this possible reason behind low HPV immunization rates, pointing out that the vaccine may be linked more to adolescent sex than cancer prevention, which is its real purpose.

A study back in October discovered that many doctors passively discourage HPV vaccination, possibly out of factors such as discomfort in discussing sexually transmitted infections, focusing on perceived high-risk groups instead of everyone in the age group, and assumptions that parents consider the vaccine unimportant.

At present, only the District of Columbia, Virginia and Rhode Island, require the HPV shot.

Early this month, the U.S. Centers for Disease Control and Prevention released an updated childhood immunization schedule, which now recommends the vaccine earlier for children with sexual abuse history.

Photo: NHS Employers | Flickr