This is a multiple-site phase 2b, randomized, placebo control study to evaluate the safety and immunogenicity of Rotavin-M1, produced by the Center for Research and Production of Vaccines and Biologicals, Vietnam.

The investigators evaluate the vaccine schedule consisting of 2 doses of Rotavin-M1, 10e6.3ffu/dose at 2 month interval in children in two study sites, Thanh Son- Phu Tho and Thai Binh city-Thai Binh provinces.

This vaccine dose and schedule was chosen based on results from the previous dose-escalating study (NCT01377571).

Inclusion Criteria:

At study entry

1. A healthy male or female, 6 to 12 weeks of age (42 days to 84 days of age).
2. Full term gestation (>=37 weeks).
3. Birth weight of the subject should be >=2.5 kg.
4. Healthy subjects as established by medical history and clinical examination before entering into the study.
5. Did not use any dose of Rota virus vaccine.
6. Written informed consent obtained from the parent or guardian of the subject.

At dose 2

1. Received dose 1.
2. Oral informed consent obtained from the parent or guardian of the subject for continuing participate the study.

Exclusion Criteria:

At study entry

1. Has a chronic disease (cardiovascular, liver, kidney disease).
2. Acute disease at the time of enrolment.
3. Administering corticosteroids (> 1mg/kg/day).
4. Received any immunosuppressive therapy within 4 week before vaccination (Administration of immunoglobulins and/or any blood product or corticosteroids for >2 weeks).
5. Immunosuppressive or immunodeficient condition.
6. Family has immunosuppressive or immunodeficient condition medical history.
7. History of high fever convulsion.
8. Allergic or reaction with any component of vaccine, includes anaphylactic shock with any antibiotic.
9. Preterm of gestation delivery (gestation period < 37 weeks).
10. Low birth weight (<2.5 kg).
11. Fever (axillary temperature >38oC) within 3 days before or on the day of vaccination.
12. Malnutrition.
13. Has any type of blood disorder, leukemia, or malignant tumor which can affect the bone marrow or lymph system.
14. Use of any investigational or non-registered product (unlicensed 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.

At dose 2

1. Acute disease at the time of 2nd dose.
2. Administering corticosteroids (> 1mg/kg/day).
3. Received any immunosuppressive therapy within 4 week before vaccination (Administration of immunoglobulins and/or any blood product or corticosteroids for >2 weeks).
4. History of allergic disease or reactions likely to be exacerbated by any component of the study vaccine.
5. Fever (axillary temperature >38oC) within 3 days before or on the day of vaccination.
6. Has any type of blood disorder, leukemia, or malignant tumor which can affect the bone marrow or lymph system.
7. Use of any investigational or non-registered product (unlicensed drug or vaccine) other than the study vaccine during the study period.