Analysis of dynamics of intensity of community immunity to diphtheria in different age groups of vaccinated population of the ryazan region in 2015-2017

Aim. To study the level of anti-diphtheria antitoxic antibodies in blood serum of vaccinated individuals over the period of 2015-2017. Materials and Methods. The study was conducted on the base of the Center of Hygiene and Epidemiology of the Ryazan region. The evaluation of antitoxic immunity against diphtheria was performed on the basis of the results of annual serological examination of at least 100 samples of blood sera for the content of diphtheria antitoxin in each age indicator group. In the study reaction of passive hem agglutination was used with standardized erythrocyte diphtheria antigen. Blood serum samples of individuals of indicator groups of the population with a documented history of vaccination were investigated. On the basis of the results of serological monitoring, the analysis of the state of anti-diphtheria antitoxic immunity in children (3-4 years, n=300), teenagers (16-17 years, n=302) and adults (30-39 years, n=323; 40-49 years, n=305) of the Ryazan region in 2015-2017 was carried out. Results. The level of protection among children, teenagers and adults in the studied period was 97.0 and 95.6%. The intensity of anti-diphtheria immunity was also high: 93.3-95.6% of the examined persons had medium and high antibody titers. Protective level of anti-diphtheria antibodies in 2015 was revealed in 97.3%, in 2016 – in 93.3% and in 2017 – in 98.3% of the examined samples. Conclusion. Analysis of the results of serological monitoring showed a positive dynamics of growth of the number of seropositive individuals with intense anti-diphtheria immunity. The data of serological monitoring correspond to the official statistical data of Directorate of Rospotrebnadzor in the Ryazan region on the high level of coverage of the population with vaccination. According to previously published epidemiological studies, in such conditions the incidence of diphtheria in the population is sporadic.