The objective of this study is to compare the antibody response 30 days after two doses of t OPV

The trial design is phase II, randomized, double blind, prospective intervention study. The subject study are 240 healthy, full term, newborn infants.

Inclusion Criteria:

• Healthy, full term, newborns infants
• newborn residing within a relatively short and easily accessible distance A(<30km) from the study clinic(s) and not planning to travel away during the entire study period
• Infant born after 37 weeks of pregnancy
• Infant weighing 2.5kg or more at birth (birth weight >= 2.5kg)
• Healthy newborns, with no history of asphyxia or meconium aspiration
• Father, mother or legally acceptable representative properly informed about the study and having signed the informed consent form.
• Parents will commit themselves to comply with the indications of the investigator and with the schedule of the trial
• Mother at least elementary school graduate

Exclusion Criteria:

• Child concomitantly enrolled or scheduled to be enrolled in another trial
• Known history of congenital or acquired immunodeficiency (including HIV infection)
• Evolving moderate or severe illness, especially infectious diseases or fever (axillary temperature >=37.5oC
• Newborns requiring hospitalization at birth
• Infant immunized with non-scheduled OPV or IPV during trial