Study of Immunogenicity & Safety of 2 Different Formulations of Human Rotavirus (HRV) Vaccine for the Prophylaxis of Rotavirus Gastroenteritis

Inclusion Criteria: * Subjects with parents/guardians who the investigator believes can and will comply with the requirements of the protocol should be enrolled in the study. * Males or females between, and including, 6 and 12 weeks (42 - 90 days) of age at the time of the first vaccination. * Written informed consent obtained from the parents or guardians of the subjects. * Healthy subjects as established by medical history and clinical examination before entering into the study. * Born after a gestation period of 36 to 42 weeks inclusive. Exclusion Criteria: * Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine within 30 days preceding the first dose of study vaccine, or planned use during the study period. * Planned administration of a vaccine (including routine paediatric vaccines) not foreseen by the study protocol during the period starting from 14 days before each dose of study vaccine(s) and ending 14 days after. * Concurrently participating in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational product (pharmaceutical product or device) * Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs since birth. (For corticosteroids, this will mean prednisone, or equivalent, 0.5 mg/kg/day. Inhaled and topical steroids are allowed.) * Any clinically significant history of chronic gastrointestinal disease including any uncorrected congenital malformation of the gastrointestinal tract or other serious medical condition, as determined by the investigator. * History of allergic diseases or reactions likely to be exacerbated by any component of the vaccine. * Any confirmed or suspected immunosuppressive or immunodeficient condition based on medical history and physical examination (no laboratory testing is required). * Major congenital defects or serious chronic illnesses. * Acute disease at time of enrolment. (Acute disease is defined as the presence of moderate or severe illness with or without fever, i.e. temperature \>= 37.5°C as measured by an axillary thermometer or \>= 38.0°C as measured by a rectal thermometer.) Temperature greater than or equal to these cut-offs warrants deferral of the vaccination pending recovery of the subject. * Gastroenteritis (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. * History of neurological disorders or seizures.