Only about half of the teenage girls in the U.S. have rolled up their sleeves for a controversial vaccine against cervical cancer ? a rate well below those for two other vaccinations aimed at adolescents. The vaccine hit the market in 2006. By last year, just 49% of girls had gotten at least the first of the recommended three shots for human papilloma virus, or HPV, a sexually-transmitted bug that can cause cervical cancer and genital warts. Only a third had gotten all three doses, the Centers for Disease Control and Prevention said Thursday. In contrast, the CDC said about two-thirds of teens had gotten the recommended shot for one type of bacterial meningitis and a shot for meningitis and tetanus, diphtheria and whooping cough. Granted, it can take many years for a new vaccine to catch on and reach the 90% and above range for many longstanding childhood vaccines. But use of HPV vaccine has been "very disappointing" compared to other newer vaccines, said the CDC's Melinda Wharton, MD.