The Food and Drug Administration announced Friday the approval of the vaccine Gardasil for the prevention of vaginal and vulvar cancer caused by Human Papillomavirus types 16 and 18 in girls and women ages nine to 26.

These two HPV types cause 70 percent of cervical cancers and are known to also cause some vulvar and vaginal cancers, but the percentages are not well defined.

The FDA originally approved Gardasil in 2006 for girls and women ages nine to 26 for the prevention of cervical cancer caused by HPV types 16 and 18, pre-cancerous genital lesions caused by HPV types six, 11, 16, and 18 and genital warts caused by HPV types six and 11.

HPV includes more than 100 related viruses and more than 30 types can be transmitted via sexual contact. According to the U.S. Centers for Disease Control and Prevention, HPV is the most common sexually transmitted infection in the United States with 6.2 million Americans becoming infected with genital HPV each year.