One of every four teenage girls took the medically prescribed vaccine for four types the human papillomavirus and cervical cancer last year, data from the Centers for Disease Control and Prevention showed.

The ratio was based on the agency's 2007 phone survey of 1,500 girls aged 13 to 17, though the health officials' recommendation is for girls to start the Gardasil vaccination as early as age 11 or 12, before sexual activity starts.

Dr. Lance Rodewald, director of the CDC's Division of Immunization Services, said the agency is targeting a 90 percent vaccination rate not only for the Merck & Co.'s Gardasil priced at $375, but also for chickenpox, hepatitis B, measles, meningitis, mumps and rubella shots for children.