The HPV vaccine may be controversial, but it works, new research shows.

The rate of HPV infection among teenage girls dropped from 11.5 percent in the “pre-vaccine era” to 5.1 percent in the “vaccine era,” researchers from the Centers for Disease Control and Prevention reported Wednesday in the Journal of Infectious Diseases. That is a drop of 56 percent, the study notes. The infection rates cover the four types of HPV that are targeted by the vaccines Gardasil and Cervarix.

Human papillomaviruses are the most common cause of sexually transmitted infections. More than half of people who are sexually active become infected with one of the more than 40 types of HPV that are known to spread during vaginal, oral or anal sex, according to the National Cancer Institute.

HPVs are responsible for nearly all cases of cervical cancer, along with most cases of anal cancer, the institute says. The viruses also cause more than half the cancers in the middle part of the throat and about half of vaginal, vulvar and penile cancers. Altogether, HPVs are responsible for about 5 percent of all cancers worldwide, according to the institute.

The CDC estimates that HPV causes 19,000 cancers in women and 8,000 cancers in men each year.

A three-dose HPV vaccine was introduced in 2006 and was recommended for girls ages 11 and 12 by the CDC’s Advisory Committee on Immunization Practices. Girls and women between the ages of 13 and 26 were advised to get a catch-up version of the vaccine.