The number of teenagers who were vaccinated for HPV last year was still unacceptably low, according to a report released today by the CDC. Despite a slight increase in vaccination rates over previous years, only 35 percent of adolescent boys and 57 percent of adolescent girls received one or more doses of the HPV vaccine by their 13th birthday in 2013. The HPV vaccine consists of three doses of a drug that adolescents receive between the age of 11 and 13. It protects against human papillomavirus, a common STD that can lead to various forms of cancer, such as cervical cancer, anal cancer, penile cancer, and throat cancer.