Only 61 percent of U.S. 13-to-17-year-olds have been fully vaccinated against the human papillomavirus, according to research published last month by the Centers for Disease Control and Prevention. The finding was based on vaccination records of over 16,500 adolescents obtained via the 2023 National Immunization Survey-Teen.

The goal was to determine rates for the four routine adolescent vaccines: for tetanus-diphtheria-pertussis, meningitis, HPV and the flu. After receiving parents’ or guardians’ consent, a complete vaccination record was collected from a mailed survey sent to the teens’ physicians.

The CDC recommends two HPV vaccine doses if starting at ages 11 or 12 and three at or after age 15. For the two-dose series, doses are separated by at least six months. If used before HPV exposure, the completed vaccination series can protect against 92 percent of cancers associated with the virus, including those of the mouth and throat and cervix, the CDC says.

Since the HPV vaccine has been in use in the United States, HPV infections and cervical pre-cancers have significantly dropped, said Cassandra Pingali, the study’s lead author.

In the 2023 vaccination survey, about 77 percent of adolescents had received at least one dose of the HPV vaccine, while only 61 percent had completed the vaccination series.

Though HPV vaccination numbers steadily increased until 2022, coverage has stalled for the second consecutive year. Of the surveyed adolescent vaccinations, HPV lags behind other routine shots.

Research from the American Academy of Pediatrics suggests that many parents of adolescents are hesitant to vaccinate because of a lack of knowledge, fears about safety or their child not being sexually active.