The human papillomavirus (HPV) vaccine is doing an excellent job of drastically reducing the cases of the disease in teens, even though immunization rates remain low.

According to the Centers for Disease Control and Prevention (CDC), about 14 million Americans become infected with HPV every year. Human papillomavirus is a sexually transmitted disease that can cause genital warts and certain types of cancer such as anal, penile, oral or cervical cancer. HPV is the primary cause of cervical cancer, a disease that kills more than 4,000 women every year, according to the American Cancer Society.

In 2006, health care professionals began recommending the HPV vaccine for tween and teen girls. In 2011, they started recommending it for boys as well.

The new data, which was published in the journal Pediatrics, looked at immunization and infection rates for girls through 2012. (Boys will be included in subsequent studies since the data on their vaccination is still too new.) Researchers compared the prevalence of HPV in women and girls of different age groups during the pre-vaccine years of 2003 through 2006 with the prevalence of the disease in the same age groups between 2009 and 2012.

The results? The prevalence of HPV in teen girls aged 14-19 had decreased by 64 percent from the pre-vaccination to post-vaccination periods. For women aged 20 to 24, the decrease was 34 percent, and for women older than 25, the incidence of the disease had not declined at all.

"These results are very encouraging and show the effectiveness of the vaccine," Dr. Lauri E. Markowitz, a medical epidemiologist at the CDC and lead author of the study, told CNN. "Eventually we expect to see decreases in HPV in older groups as women who were young (enough to get the vaccine) age," she added.

The results are promising, especially considering the low immunization rates for the vaccine. CDC data shows that while the number of girls aged 13 to 17 who received at least one dose of the HPV vaccine rose from 44 percent in 2009 to 54 percent in 2012, this rate is still low compared to other vaccines. (For comparison, the immunization rate for measles is about 92 percent.)

Health care experts understand that parents may shy away from getting a vaccine for their young daughters that will protect against a sexually-transmitted disease. But the CDC is hoping to change this thinking by working with groups like the American Cancer Society to change the focus from what causes HPV to the best ways to prevent it.

The promising results of this study may help them do just that.