Assess Efficacy, Immune Response & Safety of 2 Doses of Oral Live Attenuated HRV Vaccine at Different Viral Concentrations in Healthy Infants

Inclusion Criteria: * Healthy infants 11 and 17 weeks of age at the time of the first vaccination, born after a normal gestation period (between 36 and 42 weeks). * Written informed consent obtained from the parents or guardians of the subject. Exclusion Criteria: * Use of any investigational or non-registered drug or vaccine other than the study vaccine(s) within 30 days preceding the first dose of study vaccine, or planned use during the study period. * Previous vaccination against or history of or intercurrent diphtheria, tetanus, pertussis, polio and/or Hib. * Chronic administration of immunosuppressants or other immune-modifying drugs since birth. (Topical steroids are allowed.) * Use of antibiotics during the period starting from 7 days before each dose of vaccine(s) and ending 7 days after. * Any clinically significant history of chronic gastrointestinal disease including any uncorrected congenital malformation of the GI tract or other serious medical condition as determined by the investigator. * Any confirmed or suspected immunosuppressive or immunodeficient condition, including HIV infection. * History of allergic disease or reaction likely to be exacerbated by any component of the vaccine. * GE within 7 days preceding the study vaccine administration (warrants deferral of the vaccination). * Household contact with an immunosuppressed individual or pregnant woman. * Administration of immunoglobulins and/or blood products since birth or planned administration during the study period. * Previous confirmed occurrence of RV GE.