Assessment of herd immunity to hepatitis A virus among the population of the Republic of Tatarstan

Abstract

Introduction. Identification of the groups of the population most susceptible to infection with hepatitis A virus (HAV) is a key component for the regulation of anti-epidemic measures during the activation of the epidemic process. The aim аssessment of the herd immunity to hepatitis A (HA) among different age groups of the population of the Republic of Tatarstan. Materials and methods. The analysis of the HA incidence of from 2006 to 2021 and the study of herd immunity to HA among 6,553 persons from different age groups that were not vaccinated against HA were carried out. Participants with protective concentrations of antibodies to HAV of 20 mMU/ml or more were considered as seropositive. Results. The analysis showed a low intensity of the epidemic process in general (3.6 0.3о/оооо), while the HA incidence among children and adults was significantly different, with incidence rates 2.3 times higher in the first group (6.9 0.9 and 3.0 0.3о/оооо, respectively). The epidemic process is determined by persons aged 1517 years (8.2 2.5о/оооо), 36 years (7.0 1.9о/оооо, 714 years (6.2 1.3о/оооо), the incidence among these age groups in all observed years remained the highest. In general, the proportion of seropositive children was 32.1 1.0%. Among adults, anti-HAV IgG antibodies in a protective concentration was detected in 68.2 0.7%. The highest frequency of anti-HAV IgG positive samples was observed among persons aged 5059 years 89.4 1.1%, in age group 4049 years 73.5 1.2%, in age group 3039 years 65.5 1.3%, and in age group 2029 years 48.2 1.6%. In total, 56.9 0.6% of the examined individuals had protective antibodies to HAV. The detection rates of anti-HAV IgG antibodies were significantly different in all age groups (p 0.05).

Keywords

• viral hepatitis a
• collective immunity
• epidemic process
• protective antibodies