Phase I/II Descending Age Study of P2VP8 Subunit Parenteral Rotavirus Vaccine in Healthy Toddlers and Infants

Inclusion Criteria: * healthy infants/toddlers as established by medical history and clinical examination before entering study * age: * toddler cohort: \> or = 2 and \<3 years old at the time of enrollment * infant cohort: \> or = 6 and \<8 weeks at the time of enrollment * parental ability and willingness to provide informed consent * parental intention to remain in the area with the child during the study period. Exclusion Criteria: * Presence of fever on the day of enrollment * Acute disease at the time of enrollment * Concurrent participation in another clinical trial throughout the entire timeframe for this study * Presence of malnutrition or any systemic disorder (cardiovascular, pulmonary, hepatic, renal, gastrointestinal, hematological, endocrine, immunological, dermatological, neurological, cancer or autoimmune disease) as determined by medical history and/or physical examination that would compromise the participant's health or is likely to result in nonconformance to the protocol * For infant cohort, history of premature birth (\<37 weeks gestation) * History of congenital abdominal disorders, intussusception, or abdominal surgery * Known or suspected impairment of immunological function based on medical history and physical examination * For infant cohort only, prior receipt of rotavirus vaccine * A known sensitivity or allergy to any components of the study vaccine * History of anaphylactic reaction * Major congenital or genetic defect * Participant's parents not able, available or willing to accept active weekly follow-up by the study staff * Has received any immunoglobulin therapy and/or blood products since birth or planned administration during the study period * History of chronic administration (defined as more than 14 days) of immunosuppressant medications, including corticosteroids. Infants on inhaled or topical steroids may be permitted to participate in the study * Any medical condition in the parents/infant that, in the judgment of the investigator, would interfere with or serves as a contraindication to protocol adherence or a participant's parents' ability to give informed consent * HIV infection * For toddlers, to be assessed by HIV ELISA * For infants, to be assessed by PCR, if mother is not known to be negative (negative test result between 24 weeks gestation and screening)