RESUMEN
A study was carried out to test the efficacy of oral polio immunization commencing in the newborn period. In Group A, 47 term newborn infants were given trivalent oral polio vaccine (TOPV) within the first four days, at one month and at two months. In Group B, 21 infants were given TOPV at 3, 4 and 5 months. The seroconversion rates for types 1, 2 and 3 were 87.2, 95.7 and 72.3%, respectively in Group A and 85.7, 95.2 and 66.7%, respectively in Group B after 3 doses of TOPV, the differences being insignificant. Oral polio immunization beginning in the newborn period was as effective as when commenced at 3 months of age. Before immunization, the number of babies with protective titers against polioviruses were significantly more in Group A as compared to Group B. Thus, the later onset of immunization schedule leaves more children susceptible to poliomyelitis during the first 3 months of life.