[Results of immunization of seronegative children with live poliomyelitis vaccine].

The humoral immunity status to poliomyelitis viruses was studied in a group of children under 3 years previously immunized at least 3 times with SLV incorporated into dragee-candy. A regular increase with age of the number of subjects possessing virus-neutralizaing antibody to poliomyelitis viruses was demonstrated, the incidence of antibody to the three virus types being distributed by age groups as follows: under 1 year -- 24%, 1 year -- 53%, 2 years -- 71.2%, 3 years -- 84.8%. The immune response in children was observed to begin developing after the first vaccination mainly to one virus type. Among the children of 1--3 years of age examined, 1.1% to 6.0% had no antibody to polioviruses. An attempt was made to induce antibody production in these children by an additional vaccination with liquid SLV monitoring the implantation of the vaccine virus in the intestinal tract and seroconversion in the blood. Consecutive administration of the oral liquid vaccine of national make was found to result in immune response in 100% of vaccinees.