Nearly one in four girls who gets the human papillomavirus (HPV) vaccine mistakenly thinks that her risk of getting other sexually transmitted diseases is lowered, a new study indicates.

HPV is the most commonly transmitted sexually transmitted infection (STI) in the United States, with nearly 30 percent of sexually active girls aged 14 to 19 infected. Some virus types can raise the risk for genital warts and cervical cancer.

“I think it’s important to counsel [girls] about what the vaccine protects against,” said lead researcher Dr. Tanya Kowalczyk Mullins, an assistant professor of pediatrics at the Cincinnati Children’s Hospital Medical Center and the University of Cincinnati College of Medicine.

The findings were reported in the January issue of the Archives of Pediatric and Adolescent Medicine.

Two HPV vaccines are now licensed in the United States. One, Gardasil, protects against two HPV strains linked with genital warts and two HPV types linked with cervical cancer. Another vaccine, Cervarix, induces immunity to the two HPV types linked with cervical cancer.

The HPV vaccine is recommended by the U.S. Centers for Disease Control and Prevention for boys and girls aged 11 to 12, with catch-up immunizations recommended to the age of 26 for women and 21 for men.