Республиканский научно-практический центр эпидемиологии и микробиологии, г. Минск, Республика Беларусь 2 Республиканский центр гигиены, эпидемиологии и общественного здравоохранения, г. Минск, Республика Беларусь Популяционный иммунитет к кори в Республике Беларусь в условиях многолетней вакцинации Резюме Актульность. Несмотря на успехи, достигнутые в элиминации кори и краснухи в Европейском регионе, в настоящее время ситуация по кори ухудшилась-четыре страны региона утратили статус элиминировавших корь. Цель-оценка популяционного иммунитета к кори в Республике Беларусь, определение его возрастных и региональных характеристик для идентификации групп повышенного риска распространения инфекции. Результаты и обсуждение. Представлены результаты выполненного в 2019 г. исследования по определению уровня IgG к вирусу кори у 2229 жителей Республики Беларусь в возрасте 2-75 лет в условиях многолетнего (с 1967 г.-одна прививка, с 1987 г.-две прививки) применения вакцинации. Антитела определяли с использованием иммуноферментной тест-системы Serion ELISA classic measles virus IgG производства Virion\Serion, Германия. Выявление антител в концентрации 150 мМЕ/мл и более расценивали как свидетельство защищенности от кори. Установлено, что уровень популяционного иммунитета к кори в Республике Беларусь в 2019 г. составил 84,6%, что ниже порогового уровня (90-95%), достаточного для предотвращения широкой трансмиссии вируса в случае его завоза. Уровень серопозитивных был наиболее высоким среди детей 2-5 лет (96,9%), а также среди взрослых 46 лет и старше (93,0% и более) и не достигал 90% во всех остальных возрастных группах. Наиболее восприимчивыми к кори являлись взрослые 31-40 лет (1979-1988 года рождения)-антитела в защитной концентрации были выявлены менее чем у 80% обследованных (31-35 лет-78,9% и 36-40 лет-78,4%). Cредняя концентрация антител у серопозитивных также различалась в возрастных группах населения. Высокая концентрация (более 1000 мМЕ/мл) отмечалась у детей 2-5 лет, а также у взрослых старше 40 лет. Среди последних концентрация антител повышалась с возрастом: 41-45 лет-1069 мМЕ/мл, 46-55 лет-1212 мМЕ/мл, 56-65 лет-1582 мМЕ/мл, 66-75-1849 мМЕ/мл. Среди лиц 6-35 лет она находилась в пределах 500-600 мМЕ/мл и была несколько выше среди лиц 36-40 лет (781 мМЕ/мл). Выводы. Для дальнейшего контроля инфекции, наряду с поддержанием высокого (97% и более) уровня рутинной иммунизации, необходимо обеспечить выявление и проведение подчищающей иммунизации не привитых лиц и лиц без данных о прививках.

Study results of IgG to diphtheria and tetanus in 785 residents aged from 1 to 76 years old from different regions of the Republic of Belarus (in 2017) in long-term (since 1996) immunization schedule: at 3, 4, 5 and at 18 months old – DTP vaccine, at 6 years old – DT, at 11 years old – Diphtheria toxoid, at 16 years old, 26 years old and every following 10 years –Td or Diphtheria toxoid are presented. The antibody concentration was measured by Virion/Serion kits (Germany) and evaluated in accordance with the international standard: less than 0.01 IU/ml – individual is susceptible, 0.01–0.09 IU/ml – levels of antitoxin giving some degree of protection, 0.1 – < 1 IU/ml – protective level of circulating antitoxin, ≥ 1.0 IU/ml – a level of antitoxin giving long-term protection. It was shown that the proportion of immune individuals against diphtheria and tetanus (with antibodies ≥ 0.01 IU/ml) was 96.7% (CI 95.4 ÷ 97.9) and 99.5% (CI 99.0 ÷ 100,0), respectively, and was quite high in all the population age groups – from 87.7 to 100% for diphtheria and from 96.5 to 100% for tetanus. In seropositive individuals IgG were presented mainly in protective and highly protective (≥ 0.1 IU/ml) titers: for diphtheria 93.7% – in 1–14 years old; 88.7% – in 15–19 years old; 78.4% – in 20–76 years old and for tetanus 100.0% – in 1–14 years old; 100.0% – in 15–19 years old; 99.3% – in 20–76 years old. Comparison of the current and previous studies results (in 1989–1994 – during the outbreak of diphtheria, in 1998–2001 – after the mass immunization campaign, in 2004 – in the context of continuous single cases of diphtheria registration in adults) had shown that the data of 2017 demonstrated the highest population immunity level to diphtheria and to tetanus in the last 30 years of observation.

Relevance.Hepatitis B (HB) has a global range of spread; in the WHO European Region alone, approximately 15 million people suffer from a chronic form of infection, which in 20–30% of patients can lead to cirrhosis and liver cancer. The aim of this paper was to analyze the of the HBV epidemic process manifestations on territory of Republic of Belarus from 1965 to 2017 and to assess the epidemiological effectiveness of vaccine prevention.Materials and methods.To assess the incidence and coverage of prophylactic vaccinations against HB-infection in the general population and its individual groups, data from the state statistical reporting «Report on certain infectious and parasitic diseases and their carriers», «Report on prophylactic vaccinations», and other medical documentation were used. Results and discussion. Introduction of hepatitis B vaccination of newborns and certain adults groups allowed reducing incidence hepatitis B (HB) rate among total population by 5.4 times in 2017 (14.93 cases per 100,000 population). Incidence rate among child population decreased by 82,8 times (from 4.97 cases per 100,000 child population to 0.06 in 2016).  There is direct correlation was established between acute viral hepatitis incidence rate and vaccination coverage level (r = –0.85, p ≤ 0.05). In the last 5 years, the maximum incidence rate of all forms of HB has been marked in group of 30–39 years (68.3% of all registered cases), vaccination coverage of necessary groups is 27.9%. The total populational vaccination coverage by 01.01.2018 is 37.1%, child population is 98.0%.Conclusion.However, a certain number of children remains unvaccinated due to long-term and permanent contraindications or vaccine refuse. If achieved levels of HB vaccination are maintained over the next 20 years, population up to 40 years old will have a recommended level of immunization coverage above 98%, and population up to 45 years old – 96%. Such vaccination coverage will provide background and conditions for HB epidemic situation changing.

Relevance. The medical and social significance of hepatitis C (HC) is determined by its widespread distribution, the involvement of the working-age population in the epidemic process, the multiplicity of transmission routes of the pathogen, a variety of clinical forms, and a high frequency of chronicity and malignancy of the process. The purpose of the study - to characterize epidemic process of HC in the Republic of Belarus, based on long-term observations. Materials and methods. Assessment of the incidence of HS in the population as a whole and in individual groups was carried out according to the data of the state statistical reporting form «Report on individual infectious, parasitic diseases and their carriers» in 1996-2019. Genotyping was carried out in the core/E1 and NS5B areas; for bioinformation analysis, BoiEdit v.7.2.5, SeqA6, SeqScape v.3, and Mega 6 were used. Statistical calculations were performed using the software Statistica V.6.1 (Statsoft, USA). Credibility of long-term assessment was proved using the Spearman correlation coefficient Rs. Results. The incidence of acute hepatitis during the 24-year epidemiological observation period decreased 3.5 times from 2.68 cases per 100 ths people in 1996 to 0.76 per 100 ths people in 2019. With a downward trend in number of carriers of hepatitis C -6.34% (p < 0.05) there is still a moderate upward tendency in the incidence of chronic hepatitis C (+4.37%, p < 0.05). The age group of 21-39 years is the main cohort in the structure of patients with acute hepatitis (1.1-2.5 per 100 ths). 68.8% of all patients with chronic as well as latently occurring forms of HC are people aged 21-49, the incidence in this age group ranges from 61.3-186.2 per 100 ths and exceeds 1.3-4.5 times the incidence among the total population of Belarus. During 2018-2019 among the selected isolates, the hepatitis C was dominated by the 1st genotype represented by 1a (10.3 ± 1.7%) and 1b (51.7 ± 2.9%) subtypes and genotype 3a (31.8 ± 2.7%). Conclusion. In the Republic of Belarus the decrease in the incidence of acute hepatitis (decrease rate of -6.09% p < 0.05) comes along with the increase in the incidence of chronic hepatitis C (increase rate + 4.37% p < 0.05). The main risk group for hepatitis C is 21-49 years old. Thus, the largest share (about 70%) of disease falls on socially active population in the reproductive age with the highest labor potential (21-49 years old). The proclaimed and widely manifested decrease in the incidence of acute hepatitis is shadowed by the continued growth of newly diagnosed chronic hepatitis C in high-risk groups and it will surely worsen epidemiological situation with a large number of chronic sources of infection. The results of molecular genetic monitoring show that in the period from 2018 to 2019 the genetic structure of hepatitis C virus isolates is not different to the period of 2004-2015, and the prevailing types are still the 1b, 1a, and 3a subgenotypes of Hepatitis C virus. This knowledge is necessary for the planning, implementation and development of the Program for Elimination of Hepatitis C in the Republic of Belarus for 2019-2028, which aims to reduce HC virus infection by its prevention, detection and antiviral treatment. An expected result of the Program is a substantial decrease in mortality, disability as well as long-term job disqualification among the population of the Republic of Belarus.