I didn’t say 100% effective. I said nearly 100%.
Studies appearing in The New England Journal of Medicine in 2007 found that Gardasil was nearly 100 percent effective in preventing precancerous cervical lesions caused by the the strains that Gardasil protects against. Gardasil’s effectiveness increased when given to girls and young women before they become sexually active. Gardasil was found to be extremely effective in preventing several (but not all) of the strains of HPV known to cause cervical cancer and genital warts.
http://www.medicalnewstoday.com/releases/70808.php