Population Immunity to Varicella Zoster Virus in the Republic of Belarus

Abstract

Relevance. Chickenpox occupies a leading position in the structure of infectious pathology in the Republic of Belarus; 50,000-80,000 cases are registered annually in the country, including 2500-4500 cases among people over 15. Aims - to study the prevalence of IgG antibodies to Varicella Zoster virus among the population of the Republic of Belarus and assess the relative risk of infection for people of different ages. Materials and methods. The blood sera of 1190 people aged 2-75 from all 7 regions of the Republic of Belarus were investigated. IgG antibodies were detected using Serion ELISA classic Varicella Zoster Virus IgG, Virion\Serion, Germany. Sera with a n antibody concentration more than 100 mIU/ml were regarded as positive. The dynamics of the proportion of immune individuals by age was determined by regression analysis and estimated by the average rate of increase. To assess the risk of infection in different age groups, an indicator of the relative risk of being infected (IRR) was used. Results. It has been established that the prevalence of IgG antibodies to Varicella Zoster virus among the population of the Republic of Belarus is 85.5%, ranging from 82.0% to 89.7% in various regions of the country. The level of seropositive increases with age (from 16.0% among children aged 2 years to 86.6% by 15-17 years), it is 95.4% at the age of 18-25 years, 97.1% at the age of 26-35 years and remains at the level of 97.1-100% among older people. In the most active childbearing age of 18-35 years, 3-5% of women are susceptible to this infection. Varicella Zoster virus infection risk assessment data for people of different ages indicate that the probability of getting this infection is highest among children 3-5 years old (IRR = 98.4). In adults, it decreases many times, but in the age group of 26-35 years, it still remains two times higher (IRR = 2.0) than in people reached 46 years of age. Conclusions. The obtained data on seroprevalence are consistent with the data on morbidity and suggest that, without social management of the epidemic process (vaccination), the infection potential remains sufficient to maintain the high-intensity epidemic process among children, and medium intensity among young adults.