- Cervical cancer is one of the leading causes of cancer death in women worldwide and in Uganda. It is caused by the human papillomavirus (HPV). A vaccine against HPV was offered for all 10-year-old girls in the Nakasongola district of Uganda from October 1, 2008, to October 31, 2009. The HPV vaccine requires three doses; however, some girls received only one or two doses. Researchers want to compare vaccine immunogenicity in girls who received all three doses with those who had only one or two doses.