Programs to reduce the spread of human papillomavirus (HPV) infection work best if directed at a high percentage of girls or boys – but not both, a new study suggests. HPV is linked to the development of cervical cancer and genital warts.

Many countries, including the U.S., have started vaccinating girls, so they should stick to vaccinating girls, said study researcher Johannes Bogaards of VU University Medical Center in Amsterdam.

The findings are opposite that of a recommendation by the Centers for Disease Control and Prevention that both girls and boys receive the HPV vaccine.

In the study, researchers studied how sexually transmitted diseases are spread between heterosexuals to identify criteria that might hamper its spread. They found vaccinating just one sex was the most effective way to reduce infections because vaccinating one protects the other. However, they note, it’s important to attempt to vaccinate as many of that one sex as possible.

For example, vaccinating 100 percent of women and no men will provide better HPV protection than vaccinating 50 percent of both sexes.

HPV is more prevalent in women because it causes longer, more persistent infections, Bogaards said.