The figures represent the U.S. government's first full year of vaccination rate data for the Gardasil vaccine, which came on the market in mid-2006. Merck & Co.'s heavily advertised, three-shot series targets the sexually transmitted human papillomavirus.
Health officials recommend that girls get the shots when they are 11 or 12, if possible, before they become sexually active. Also, age 11 is when kids are generally due for another round of vaccinations.
The survey only covered children in the 13-17 age range.
Vaccine proponents had been hoping for much higher vaccination rates, saying the shots could dramatically reduce the nearly 4,000 cervical cancer deaths that occur each year in the United States.
But many families are cautious about the safety of new vaccines, said Patti Gravitt, a Johns Hopkins University associate professor of epidemiology.
Other things about the vaccine may give some families pause. It is expensive, retailing for about $375, although many health insurers now cover it. And there are questions about whether it confers lifetime immunity or if a booster shot will be needed.
"Some parents may be adopting the attitude with their daughters that, 'Well, you're still young. I can wait a couple more years before you're sexually active,"' said Gravitt, who was not involved in the research.
"My personal opinion is that this seems quite reasonable after the first year," Gravitt said, of the 25 percent vaccination rate.
Merck officials said they were pleased with the vaccination rate.
The Centers for Disease Control and Prevention based the study on household telephone surveys done in late 2007. The results are based on nearly 3,000 teens ages 13 to 17 for whom the researchers could verify vaccination information through medical records.
Of the girls in the survey, 25 percent had gotten at least one Gardasil shot.
The CDC, which has been promoting other shots for adolescents, also studied other teen vaccination rates.
About 32 percent of teenagers got a recommended meningitis shot last year, up from 12 percent in a 2006 survey. Also, 30 percent got another relatively new shot, one that guards against tetanus, diphtheria and whooping cough. That's up from 11 percent the year before.
As with the cervical cancer shot, health officials say children should get both those shots when they are 11 or 12.
About 75 to 90 percent of children got the better-known vaccinations that have long been required by schools, such as chickenpox, hepatitis B and measles, mumps and rubella, the study found.
"The overall trends are good news," said Dr. Lance Rodewald, director of the CDC's Division of Immunization Services, in a prepared statement.
"We are seeing more preteens and teenagers being protected against serious, sometimes deadly diseases. But we remain short of our goals. For almost all of these vaccines we want at least 90 percent of adolescents to be fully immunized."