According to the Associated Press, the U.S. Food and Drug Administration has approved the drug, manufactured by Merck Pharmaceuticals, to guard against cancers that attack the vagina and vulva.

Gardasil fights most strains of the human papillomavirus (HPV) that cause cervical cancer. About 20 million Americans carry HPV, but not all of them develop cancer. About 5,000 women get vulva and vaginal cancer annually, according to the wire service.

"Anytime we have evidence of additional cancer protection, that's a really important piece of information," the AP quotes Rick Haupt, Merick's executive director for HPV vaccines, as saying.

More information

The U.S. Centers for Disease Control and Prevention has more information about this drug.