Each phase of the study (Part I onwards) will be completed and based on the development, and progress, the next phase will be initiated. If the vaccine is found to be without adverse effects on the adults it will be tested in the children, 2-5 years of age and followed by the younger age group 12-23 months of age. The results will be presented to the Data Safety Monitoring Board after completing the safety surveillance part of each phase of the study and before proceeding to the next study group.