Researchers say the number of teenage girls and young women contracting HPV has significantly decreased since 2006, but the percentage of females getting the vaccination is still too low.

Researchers say they now have data to back up their contention that a vaccine for the human papillomavirus (HPV) can significantly reduce the disease in teenage girls and young women.

In a report published today in the journal Pediatrics, researchers said the prevalence of HPV among girls ages 14 to 19 in the United States fell 64 percent in the first six years after the vaccine was introduced in 2006.

The report from researchers at the Centers for Disease Control and Prevention (CDC) also stated that the prevalence of HPV among women 20 to 24 years of age dropped 34 percent.

“We are excited by the fact that there is a growing impact by this vaccination program,” Dr. Lauri Markowitz, a CDC medical epidemiologist and lead author of the study, told Healthline. “This is one of our most effective vaccines.”

The report comes just weeks after the CDC issued new guidelines on when girls and boys should begin to get the three recommended doses of the HPV vaccine.

In those guidelines, CDC officials recommended children start getting the vaccine at age 11 to provide immunity before they become sexually active.

Read More: CDC Continues Aggressive Push for HPV Vaccine »

In their report, CDC officials said the percentage of girls ages 14 to 19 who contracted HPV in the United States dropped from 11.5 percent of that population from 2003 to 2006 to 4.3 percent from 2009 to 2012.

They also stated the percentage of women 20 to 24 years infected with HPV fell from 18.5 percent to 12.1 percent during that same time period.

The researchers also said almost 17 percent of sexual active females from ages 14 to 24 who hadn’t been vaccinated contracted HPV. That was about the same percentage as before the introduction of the vaccine.

In contrast, only 2 percent of sexually active females in the same age group who had received the vaccine contracted the disease.

The numbers were gleaned from the National Health and Nutrition Examination Surveys (NHANES).

Read More: Teens Are Missing HPV Vaccinations Because Doctors Are Reluctant to Talk About Them »

The HPV vaccine prevents nine different kinds of cancer, including cervical cancer, as well as genital warts, according to medical experts.

It’s also covered by most health insurance plans.

Nonetheless, the CDC researchers reported, only about 42 percent of girls and 22 percent of boys between the ages of 13 and 17 have received the three-dose vaccine series.

Markowitz said there may have been some hesitancy early on from both parents and medical professionals in recommending the vaccine.

She hopes this new data will spur more participation.

Dr. Carrie Byington, the endowed chair of the department of pediatrics at the University of Utah School of Medicine, told Healthline that early fears that the vaccine would increase sexual activity or sexually transmitted diseases among girls have proven to be untrue.

“Vaccine history is not something a teenager uses to become sexually active,” Byington said.

She added now is the time for medical professionals to talk up the positive aspects of the vaccine.

“We need to emphasize that this is a cancer prevention vaccine,” Byington said.

She and Markowitz said educating parents as well as doctors and other medical professionals is a key to boosting immunization rates.

“We need to communicate better with parents and families,” Byington said.

Read More: HPV Vaccine Doesn’t Lead to More Unsafe Sex or Sexually Transmitted Diseases »