This is a pilot study to assess the safety and immunogenicity of pentavalent rotavirus vaccine (RV5) when administered according to an alternate dosing schedule (2-5 weeks, 2 months and 4 months). In this interventional, open-label study, infants 2 through 5 weeks of age (14 to 41 days) will be enrolled and vaccinated with RV5 according to a 2-5 week, 2 and 4 month schedule and infants 2 months of age (56 to 83 days) will be vaccinated according to the standard recommended schedule (2, 4, and 6 months of age). Sera will be obtained from subjects one month following the final dose of vaccine and will be assayed for anti-rotavirus IgA and rotavirus neutralizing antibody responses against the G1, G2, G3, G4 and P[8] serotypes. Post dose 3 G1 serum-neutralizing antibody (SNA) geometric mean titers (GMTs) will be compared between children receiving pentavalent rotavirus vaccine (RV5) according to the alternate dosing schedule versus the standard recommended schedule. Likewise, post dose 3 G2, G3, G4 and P[8] SNA and serum rotavirus IgA GMTs will be compared between children receiving RV5 according to the alternate dosing schedule and the standard recommended schedule. The safety and tolerability of RV5 in children receiving vaccine according to the alternate dosing schedule will be described.

Inclusion Criteria:

1. Male or female infants who are 14 through 41 or 56 through 83 days of age at Visit 1 (Day of initial vaccination)
2. Parent / legal guardian has read and signed the informed consent document
3. Child and parent / legal guardian is available for the entire study period and can be reached by telephone
4. Healthy infant as determined by medical history and by a baseline physical examination
5. Infant weight at time of enrollment must exceed birth weight

Exclusion Criteria:

1. History of hypersensitivity to the vaccine or any component of the vaccine
2. History of Severe Combined Immunodeficiency Disease (SCID)
3. History of immunocompromise ( infant is known to be HIV positive, to have hypogammaglobulinemia or to have an underlying malignancy)
4. History of intussusception
5. Any clinically significant history of gastrointestinal disease including active acute gastrointestinal illness, chronic diarrhea, failure to thrive, congenital abdominal disorders, abdominal surgery or liver disease
6. Prior receipt of a rotavirus vaccine
7. Less than 37 weeks gestation
8. The subject has participated in a study with an experimental agent within one month of enrollment in the study or anticipated receipt of an experimental agent during participation in the study
9. Receipt of blood products within 4 weeks of study vaccination
10. Receipt of a live virus vaccine within 4 weeks of study vaccination or an inactivated vaccine within 2 weeks. Concomitant administration of routinely recommended vaccines is allowed. A dose of hepatitis B vaccine administered in the birthing hospital is permitted. Planned routine use of inactivated influenza vaccine for children over 6 months of age is permitted.
11. Acute illness within 48 hours of vaccination (axillary temperature of 100.4°F or higher, 3 or more grossly watery stools, vomiting). (Infants with stable unchanged gastroesophageal reflux may be enrolled).
12. Insufficient weight gain requiring future weight checks in addition to routine scheduled well child visits
13. The subject has any condition that the investigator believes would put the subject at an increased risk of injury or would render the subject unable to complete the trial or fulfill the requirements of the study protocol.
14. Household contact who is immunodeficient (any malignancies or otherwise immunocompromised, primary immunodeficiency, receiving immunosuppressive therapy)

7 days after each dose, up to 10 months post-vaccination

Proportions of subjects in each vaccine group reporting a reactogenicity event in the period following each dose and any dose of RV5 will be determined.

Open Label