This is a randomized, double-blind, phase 3 study to evaluate the Efficacy,Safety, and Immunogenicity of ROTAVAC 5D, a live attenuated rotavirus vaccine in healthy infants aged 6-8 weeks.

A total of 5800 healthy Chilean infants will be recruited in this study and randomized to receive either vaccine or placebo in 1:1 ratio. Among these participants 300 will be categorized to immunogenicity cohort, 150 from each group, and blood samples will be collected to assess the immune response.

The Efficacy of Three Doses of Live Attenuated, Oral Rotavirus Vaccine 116E (ROTAVAC 5D) in Chilean Infants.

This is a randomized, double-blind, phase 3 study to evaluate the Efficacy, Safety, and Immunogenicity of ROTAVAC 5D, a live attenuated rotavirus vaccine in healthy infants aged 6-8 weeks.

A total of 5800 healthy Chilean infants will be recruited in this study and randomized to receive either vaccine or placebo in 1:1 ratio. Among these participants 300 will be categorized to immunogenicity cohort, 150 from each group, and blood samples will be collected to assess the immune response. Inclusion At least one parent(s) or legally acceptable representative's consent for participation and are able to understand study procedures Subjects aged 6 to 8 weeks at recruitment No plans to move in the next 12 months Exclusion Administration of rotavirus vaccine in the past Presence of any illness requiring hospital referral (temporary exclusion) Known case of immunodeficiency disease, known HIV positive Known case of chronic gastroenteritis disease, chronic pulmonary disease, chronic renal disease, congenital heart disease Any other conditions which in the judgment of the investigator warrant exclusion (e.g. no exclusion criteria but seems 'ill', investigators suspects neglect) Diarrhea on the day of enrollment (temporary exclusion) A known sensitivity or allergy to any components of the study vaccines. Major congenital or genetic defect. Has received any immunoglobulin therapy and/or blood products since birth. History of chronic administration (defined as more than 14 days) of immunosuppressants including corticosteroids. Infants on inhaled or topical steroids may be permitted to participate in the study, at the discretion of the principal investigator. Blood samples: In the "Immunogenicity Subset", 3 ml blood specimens will be collected at baseline and 28 (+) 5 days after the third dose of the Test Article/placebo to assess the anti rotavirus IgA antibody titer. Stool Specimens: The study team will attempt to collect a stool specimen for every GE episode, preferably within the first 2 days after episode onset. The stool specimen may be collected up to 7 days after the last day of diarrhea. The stool specimens will be sent to the laboratory. If the episode is a suspected intussusception or vaccine associated gastroenteritis that has occurred within four weeks after each dose of the Test Article/placebo, the specimen will be sent to the laboratory immediately for rotavirus testing and typing. For all ELISA RV positive samples, an aliquot of the stool specimen will be assessed for 20 enteropathogens by multiplex-PCR panel and to identify the genotype of the virus.

Inclusion Criteria:

1. At least one parent(s) or legally acceptable representative's consent for participation and are able to understand study procedures
2. Subjects aged 6 to 8 weeks at recruitment
3. No plans to move in the next 12 months

Exclusion Criteria:

1. Administration of rotavirus vaccine in the past
2. Presence of any illness requiring hospital referral (temporary exclusion)
3. Known case of immunodeficiency disease, known HIV positive
4. Known case of chronic gastroenteritis disease, chronic pulmonary disease, chronic renal disease, congenital heart disease
5. Any other conditions which in the judgment of the investigator warrant exclusion (e.g. no exclusion criteria but seems 'ill', investigators suspects neglect)
6. Diarrhea on the day of enrollment (temporary exclusion)
7. A known sensitivity or allergy to any components of the study vaccines.
8. Major congenital or genetic defect.
9. Has received any immunoglobulin therapy and/or blood products since birth.
10. History of chronic administration (defined as more than 14 days) of immunosuppressants including corticosteroids. Infants on inhaled or topical steroids may be permitted to participate in the study, at the discretion of the principal investigator.