Serology for each serotype will be performed by enzyme immunoassay and immunogenicity endpoints will include seroprotection rate (SP) (percentage of subjects achieving antibodies titers ≥1.3 micrograms/mL), seroconversion rate (SC) (percentage of subjects with a minimum of 2-fold rise in post-vaccination antibodies titers) and the geometric mean concentration of antibodies (GMC). Adequate vaccine response will be considered when SC occur for at least 50% of all seven vaccine serotypes.