Rotavirus is one of the most common causes of severe diarrhea, responsible for 40% of all diarrhea related deaths in children worldwide. Two vaccines against Rotavirus, Rotarix® and Rotateq® were licensed in many high and middle income countries in 2006, but lack of efficacy data in low income countries had prevented WHO from making a universal recommendation of their use until recently. This study will be conducted in Pakistan and will look at two objectives:

1. To compare the immunogenicity of Rotarix® vaccine when administered at 6 and 10 weeks of life and at 6, 10 and 14 weeks of life.
2. To compare the immunogenicity of Rotarix® vaccine in infants breast fed at the time of vaccine administration with infants whose breast feeding is withheld for one hour before and after vaccine administration.

Inclusion Criteria:

• 6 weeks 0 days to 6 weeks 6 days age at the time of enrollment.
• Healthy infant free of chronic or serious medical condition as determined by history and physical exam at time of enrollment into in the study.
• Written informed consent obtained from the parents or guardians.

Exclusion Criteria:

• Hypersensitivity to any of the vaccine components.
• Use of any investigational drug or vaccine other than the study vaccine within 30 days of first dose of study vaccine or during the study.
• Use of any immunosuppressive drugs.
• Previous intussusception or abdominal surgery.
• Enrolment in any other trial (Simplified Antibiotic Therapy for Neonatal Sepsis Trial, Management of Omphalitis Trial).
• Birth weight less than 1500 grams; or if birth weight is unknown, weight less than 2000 grams on or before 28 days.
• Immunoglobulin and/or blood products use since birth or during the study period.