Estudios sobre la vacuna antipoliomielítica trivalente administrada por vía oral en una o dos dosis a niños de México

Abstract

The antigenic capacity of one and of two doses of Lederle-Cox oral trivalent poliomyelitis vaccine was studied in a group of children aged from 6 months to 5 years living in Huitzilac (Morelos) and of Tlaxcala (Tlaxcala) in Mexico

The serologic conversion rate obtained with one dose in both villages was 32.3 per cent, 25.1 per cent, and 72.8 per cent for Types 1, 2, and 3, respectively. In a group of children in Tlaxcala the conversion percentage with two doses was 55.7 per cent for Type 1, 43.8 per cent for Type 2, and 89.3 per cent for Type 3. The Markham seronegativity index was 75.7 per cent before the vaccination and 28.6 per cent after the administration of the two doses. It should be noted that the second dose produced a higher conversion percentage than the first, especially in triple-negative children

Although in general it is pointed out that the component of Type 2 of this vaccine is the least antigenic - as was confirmed by this study - that of Type 1 of the lot tested was also defective. The reasons for the low potency of the lot used are discussed. Mention is also made of the interference of the natural enteric viruses with the vaccine strains. The degree of dissemination of the latter to susceptible contacts was estimated to be around 8 per cent

During the study no cases of paralytic poliomyelitis or pathological manifestation attributable to the vaccine were observed(AU)