Clinical adverse events will be monitored and relatedness to vaccine/placebo administration assessed for 14 days after each administration of the dosage under study, whereas monitoring for symptoms of intussusception will be assessed throughout the 28 day follow up period. Laboratory adverse events will be monitored for upto 28 days after first administration of each dosage. After the 4 week follow up of the third administration of the vaccine/placebo of the lowest dosage (10^4.0) is completed for all enrolled infants and the data safety monitoring board (DSMB) meeting will be convened and the data from the study will be analyzed, the code broken. If the DSMB declares the dosage safe, guided by the apriori criteria, the team will move on to screening infants for the next higher dosage (10^5.0) and the strategy listed above will be repeated for a total of 180 enrolled infants (90 vaccinees/90 placebo). The DSMB will again meet to review the data available from this cohort (i.e. 10^5.0) and the team will proceed to screen infants for the next higher dosage (10^6.0) only if the former is declared safe.