Immunization of Preschool Children with Oral Poliovirus Vaccine (Sabin)

The effectiveness of an oral polivirus vaccine using Sabin strains was studied among some 350 preschool children beginning in January, 1960. Although 79% of the children had previously received 3 or more doses of killed virus vaccine, a relatively high per cent lacked antibody to one or more types, and 22% of 348 children were triple negatives. The oral vaccine was given according to 3 different dosage schedules: each type singly; Type 1 followed by Types 2 and 3 together; and trivalent vaccine twice, 6 weeks apart. The infection and antibody conversion rates were similarly high for all 3 schedules, the overall conversion rates being 95% for Type 1, 98% for Type 2, and 86% for Type 3. The results emphasize the desirability of oral vaccine for young preschool children regardless of previous administration of multiple doses of killed Salk-type vaccine.