It has been nearly a decade when the human papillomavirus (HPV) vaccine was first recommended for girls but a new study has revealed that only three states in the U.S namely Virginia, Rhode Island and Washington D.C. require kids to be immunized.

The HPV vaccine provides protection against several strains of the sexually-transmitted papillomavirus, which cause genital and anal warts that can lead to cancer. Most cases of cervical cancers are attributed to HPV and the virus is also known to contribute to vulvar, anal and vaginal tumors.

The vaccine was green-lighted in 2006 after which the U.S. Centers for Disease Control and Prevention Advisory Committee on Immunization Practices recommended that girls and boys between 11 and 12 years of age should receive the vaccine.

Health officials also said that women up to age 26 should get the shots, an advice that was eventually recommended to men as well.

As of 2013, data from the CDC revealed that only half of girls and fewer boys completed the recommended three dose series of the vaccine.

Right now, only Washington D.C and Virginia require vaccination and Rhode Island will follow them in August after passing its own regulation. Study researchers noted that Virginia and D.C. even have broad exemptions. If parents do not want their child vaccinated against HPV, they can still send their kids to school.

"Vaccination coverage is substantially below the Healthy People 2020 target of 80 percent," wrote study researcher Jason Schwartz, from Princeton University in New Jersey, and colleagues. "Recent efforts to address these deficits emphasize that HPV vaccines should not be viewed or treated differently than other routinely recommended vaccines."

Experts said that strong recommendations from doctors would help boost the HPV vaccination rates. Making more parents aware of the immunization's potential benefits may also help.

"Since the vaccine was first recommended in 2006, there has been a 56 percent reduction in vaccine type HPV infections among teen girls in the U.S., even with very low HPV vaccination rates," said a CDC spokesperson. "Research has also shown that fewer teens are getting genital warts."

Schwartz said that while some parents are concerned that the vaccine gives kids inferred approval to engage in sexual activities, they have clear evidence based on a number of studies that the vaccine does not encourage sexual activity.

The study was published in the Journal of the American Medical Association on July 14.

Photo: NIAID | Flickr