The immunogenicity of Silgard was assessed in 8,915 (Silgard n = 4,666; placebo n = 4,249) women 18 to 26 years of age and 3,400 female (Silgard n = 1,471; placebo n = 583) and male (Silgard n = 1,071; placebo n = 275) adolescents 9 to 17 years of age.