In the genital tract human papilloma virus (HPV), especially types 6 and 11 cause genital warts, the commonest viral sexually transmitted disease. The HPV 16 and 18 are the most common oncogenic "high-risk" genotypes and cause approximately 70% of all cervical cancers despite the fact that are associated with other anogenital cancers, anus, vagina, vulva and penis, and cancers of the head and neck. Current estimates are that 5.2% of all cancers are HPV associated. A large number of studies, including both adult and young females, have demonstrated that HPV vaccines are highly immunogenic and induce a long lasting protection against infection. Immunogenic vaccination results in young men and boys are equally satisfactory with the quadrivalent HPV (types 6, 11, 16, 18) vaccine recommended for men. The recommended vaccination scheme includes three shots giving the second at two months and the third at six months after the initial shot. Recently, it has been shown that the use of a two shot scheme (0 and 6 months) is equally effective among girls. The purpose of this study is to determine that the immunogenicity is non-inferior in boys using a two shot scheme compared with young women and girls.

Inclusion Criteria:

• All those children whose parents accept their participation in the study.

Exclusion Criteria:

• Fever,
• previous vaccination against HPV,
• allergy to vaccine components,
• thrombocytopenia,
• immunosuppression,
• diarrhea,
• vomiting,
• dyscrasia,
• administration of another anti-viral vaccine in the previous 15 days.