[A trial of using immunoglobulins of known specificity for preventing hepatitis A in regions with high epidemic activity]. / Opyt primeneniia immunoglobulinov s izvestnoi spetsifichnost'iu dlia profilaktiki gepatita A v regionakh s vysokoi aktivnost'iu épidemicheskogo protsessa.

The economic effectiveness of immunoglobulin prophylaxis (IGP), carried out among children aged 1-3 at the beginning of a seasonal rise in hepatitis A (HA) morbidity with high coefficients of protection (80-85%), was directly related to the activity of the epidemic process. Preparations with sufficiently high content of antibodies to HA virus sharply decreased the manifestation of this infection. The detection rate of the manifest forms of the infection among children covered by prophylactic measures in the foci of HA was considerably lower than among children who had not received the preparation. IGP exerted no essential influence on the dynamics of the formation of population immunity. A high share of children aged 3-4 years, seropositive to HA virus (up to 90%), validates the inadvisability of carrying out IGP in older groups of children.

[Specific immunity in preschool children at high risk of infection with hepatitis A virus]. / Spetsificheskii immunitet u detei preshkol'nogo vozrasta v usloviiakh vysokogo riska infitsirovaniia virusom gepatita A.

The dynamics of postinfection immunity to hepatitis A (HA) in preschool children was studied for 2 years in an area with a high activity of the epidemic process. In primary examinations by radioimmunoassay, anti-HAV were found in 82% of the subjects. The degree of the immunity intensity was found to be markedly variable: in 21% of the children the titre of anti-HAV was 1:10, in 28%-1:40, in 37%-1:160, in 14%-1:640. One year later, in the group of children with titres 1:10-1:40 the antibody level increased from 4- to 64-fold in 66% of the subjects. The rate of increase expressed in mean coefficients of antibody rise were the higher the lower the initial anti-HAV titres were. In the children with the initial titre below 1:10 this value approached 100, and anti-HAV-IgM were found in half of the examined subjects, one third of them having experienced the jaundice form of HA. The children with titres of 1:10-1:40 were found to have both manifest (14% and 11%, respectively) and asymptomatic (only anti-HAV-IgM) forms of HA. In the group of children with titres of antibody of 1:160-1:640 neither manifest HA forms nor anti-NAV-IgM could be detected. In this group the anti-HAV titre increased 4-fold or more in only 9% whereas a decrease was observed in 59% (with titre of 1:160) and in 73% (with titre of 640). No changes in anti-HAV levels were observed in 32% and 18%, respectively. Thus, the results of the study indicate that at low levels of postinfection immunity reinfection with HAV is possible and may run both manifest and asymptomatic course.