- To determine the protective effect of the HPV-6, -11, -16, -18 vaccine in preventing anogenital lesions associated with HPV 6,-11,-16, -18 and persistent infection with these types, in HIV-positive MSM age 13-26 years by comparing the incidence of lesions and persistent infection among those naïve to the relevant types at baseline to incident lesions and infection among MSM naïve to these HPV types who participated in the Merck 020 protocol and who received placebo as part of the protocol.