The 25.1 percent vaccination rate among 13- to 17-year-olds provides the first national estimate of use of Merck & Co.'s Gardasil vaccine, the Centers for Disease Control and Prevention said.

Gardasil, administered in a three-dose series, is a vaccine against certain types of human papillomavirus, which infects the skin and mucous membranes.

Human papillomavirus, or HPV, infection causes nearly all cases of cervical cancer, the second leading cause of death from cancer in women worldwide.

Nearly 4,000 women die of cervical cancer in the United States each year.

"For a new vaccine, 25 percent coverage is really very good," Immunization Services Director Lance Rodewald said.

Vaccine proponents had hoped for higher vaccination rates.

Both men and women can be HPV carriers. Studies are being conducted to determine the efficacy of vaccinating boys with Gardasil.