In the fight against coronavirus infection, control of the immune response is of decisive importance, an important component of which is the seroprevalence of antibodies to SARS-CoV-2. Immunity to SARS-CoV-2 is formed either naturally or artificially through vaccination. The purpose of this study was to assess the seroprevalence of antibodies to SARS-CoV-2 in the population of Kyrgyzstan. A cross-sectional randomized study of seroprevalence was carried out according to a program developed by Rospotrebnadzor and the St. Petersburg Pasteur Institute, taking into account WHO recommendations. The ethics committees of the Association of Preventive Medicine (Kyrgyzstan) and the St. Petersburg Pasteur Institute (Russia) approved the study. Volunteers (9471) were recruited, representing 0.15% (95% CI 0.14–0.15) of the total population, randomized by age and region. Plasma antibodies (Abs) to the nucleocapsid antigen (Nag) were determined. In vaccinated individuals, Abs to the SARS-CoV-2 receptor-binding domain antigen (RBDag) were determined. Differences were considered statistically significant at p < 0.05. The SARS-CoV-2 Nag Ab seroprevalence was 48.7% (95% CI 47.7–49.7), with a maximum in the 60–69 age group [59.2% (95% CI 56.6–61.7)] and a minimum in group 1–17 years old [32.7% (95 CI: 29.4–36.1)]. The highest proportion of seropositive individuals was in the Naryn region [53.3% (95% CI 49.8–56.8)]. The lowest share was in Osh City [38.1% (95% CI 32.6–43.9)]. The maximum SARS-CoV-2 Nag seropositivity was found in the health-care sector [57.1% (95% CI 55.4–58.8)]; the minimum was seen among artists [38.6% (95% CI 26.0–52.4)]. Asymptomatic SARS-CoV-2 Nag seropositivity was 77.1% (95% CI 75.6–78.5). Vaccination with Sputnik V or Sinopharm produced comparable Ab seroprevalence. SARS-CoV-2 Nag seropositivity in the Kyrgyz population was 48.75% (95% CI 47.7–49.7), with the mass vaccination campaign undoubtedly benefitting the overall situation.

Historically, viral hepatitis has been a considerable public health problem in Central Asian countries, which may have worsened after the dissolution of the Soviet Union. However, up-to-date seroepidemiological studies are lacking. The aim of the present study was, therefore, to provide current estimates of the seroprevalence of viral hepatitis in Kyrgyzstan, one of the economically least developed countries in the region. We conducted a population-based cross-sectional study in 2018 in the capital of Kyrgyzstan, Bishkek (n = 1075). Participants, children and adults, were recruited from an outpatient clinic. The data were collected during face-to-face interviews. A blood sample (6 mL) was collected from each participant and tested with ELISA for the presence of serological markers for five viral hepatitides (A, B, C, D, and E). Post-stratification weighing was performed to obtain nationally representative findings. The overwhelming majority of the study participants were positive for anti-HAV (estimated seroprevalence, 75.3%; 95% confidence interval, 72.5–77.9%). The weighted seroprevalence estimates of HBsAg, anti-HCV, and anti-HDV were 2.2% (1.5–3.3%), 3.8% (2.8–5.1%), and 0.40% (0.15–1.01%), respectively. Anti-HEV seropositivity was 3.3% (2.4–4.5%). Of the 33 HBsAg-positive participants, five (15%) were anti-HDV-positive. Our study confirms that Kyrgyzstan remains a highly endemic country for hepatitis virus A and C infections. However, seroprevalences of HBV and HDV were lower than previously reported, and based on these data, the country could potentially be reclassified from high to (lower) intermediate endemicity. The observed anti-HEV seroprevalence resembles the low endemicity pattern characteristic of high-income countries.

Specific prevention of measles, mumps, and rubella (MMR) is the main prerequisite for a radical reduction in the incidence of these infections in the Kyrgyz Republic (KR). An increase in the number of seronegative individuals observed in recent years has led to an increase in measles incidence. This is directly related to a decrease in collective immunity, which provides protection for the population only in conditions of a high density of immunized individuals and their uniform distribution in the population. The only way to estimate the number of immunized individuals is by conducting serological surveys of collective immunity. Aim of the study: The aim was to study the level of collective immunity to the MMR viruses in the KR. Materials and methods: This study involved a cohort of 6617 residents (volunteers) aged 1 to 70⁺ years, formed in accordance with the Rospotrebnadzor program “Assessment of collective immunity to vaccine-preventable and other relevant infections” and stratified by age and region of residence. During the study, participants filled out a questionnaire and gave venous blood samples to determine IgG antibodies to MMR viruses (ELISA using certified Russian test systems). Results: In December 2023, collective immunity ensured epidemiological well-being only with respect to rubella. The volunteer seropositivity was 94.2% (95% CI: 93.7–94.8). The average measles seropositivity was 78.9% (95% CI: 77.9–79.9). It was significantly lower in children aged 1–17 years and significantly higher than the cohort average in individuals aged ≥18 years. The average mumps seropositivity was 76.4% (95% CI: 75.3–77.4), with the minimum level noted among individuals aged 12–29 years (63.8%; 95% CI: 61.4–66.2). The maximum levels of mumps seropositivity were noted among children aged 6–11 years and older adults who had likely experienced mumps (50–70⁺ years). Seroprevalence distributions by activity correlated with age distributions (all infections). Conclusions: The system of targeted prophylaxis of vaccine-preventable infections adopted in the KR has contributed to the formation of a high level of rubella collective immunity and, to a lesser extent, measles and mumps immunity. The recent trend towards increases in measles and mumps incidence in the KR requires additional efforts to increase collective immunity to these infections.

Vaccination against hepatitis B virus (HBV) is the most cost-efficient measure to prevent infection. Still, vaccination coverage among adults in Central Asia, including Kyrgyzstan, remains suboptimal, and data about immune responses to HBV vaccination are lacking. HBV vaccination is given as three injections, whereby the second and third doses are given 1 and 6 months after the first (0-1-6 scheme). However, compliance with the third dose is low in Kyrgyzstan, presumably due to the long time interval between the second and third doses, suggesting that a shortened vaccination schedule could result in better adherence and increased seroconversion. Thus, we conducted a randomized trial of individuals aged 17–66 years comparing the 0-1-6 scheme against a shorter 0-1-3 scheme. Primary outcome measures were post-vaccination titers and the percentage of participants with protective post-vaccination titers (≥10 mIU/mL). Compliance with the completeness of blood draws and administered third vaccine dose was better with the 0-1-3 scheme than with the 0-1-6 scheme. In both study arms combined, younger age (<40 years) was associated with better vaccine protection. The 0-1-6 scheme resulted in higher post-vaccination titers (52 versus 15 mIU/mL, p = 0.002) and a higher seroprotection rate (85% versus 64%, p = 0.01) than the 0-1-3 scheme, whereby post-vaccination titers correlated negatively with age in the 0-1-3 scheme. Thus, the 0-1-6 scheme should continue to be the preferred HBV vaccination schedule, but interventions to improve compliance with the third vaccine dose are needed.

Введение. Вирусные гепатиты (ВГ) В и С остаются одной из основных проблем общественного здравоохранения, которая обусловленная высоким распространением, тяжестью течения и тяжелыми социально экономическими последствиями. По данным ВОЗ регионами с высоким распространением вирусных гепатитов В и С являются страны Африки к югу от Сахары, страны Центральной и Восточной Азии. Цель публикации описать результаты ретроспективного анализа распространенности гемоконтактных вирусных гепатитов (ГКВГ) В и С в КР. Методы и материалы. Материалами служили отчетные данные ЦЭЗ МЗ КР и ДПЗ и ГСЭН за период с 1998 по 2021гг. Проведена оценка многолетней динамики заболеваемости с использованием метода наименьших квадратов. А также использовались стандартные методы статистической обработки данных в программе Excel. Результаты. За анализируемый период (1998-2021 гг.) заболеваемость ВГВ снизилась в 15 раз (с 27,7 до 1,8 на 100 тыс. населения). Показатели заболеваемости ВГС в диапазоне от 0,8 (2021) до 2,3 (2010; 2012) на 100 тыс. населения. В возрастной структуре по ВГ В и С наибольшую долю занимает возрастная группа 18-49 л. (80,6% и 67,9 % соответственно). Выводы. В КР официальная регистрация новых случаев, ГКВГ В и С осуществляется только по обращению пациентов, поэтому не отражает реальную ситуацию распространения ВГ. Резкое снижение заболеваемости от ВГВ связано с внедрением обязательной вакцинации против ВГВ в календарь прививок, в связи с этим для снижения заболеваемости ВГВ следует внедрить плановую вакцинацию взрослого населения до 49...

Historically, viral hepatitis is a considerable public health problem in Central Asian countries, which may have worsened after dissolution of the Soviet Union. However, up-to-date seroepidemiological studies are lacking. The aim of the present study was, therefore, to provide current estimates of seroprevalence of viral hepatitis in Kyrgyzstan, one of the economically least developed countries in the region. We conducted a population-based cross-sectional study in 2018 in the capital of Kyrgyzstan, Bishkek (n=1075). Participants, children and adults, were recruited from an outpatient clinic. Data were collected during face-to-face interviews. A blood sample (6 ml) was collected from each participant and tested with ELISA for the presence of serological markers for five viral hepatitides (A, B, C, D and E). Poststratification weighting was performed to obtain nationally representative findings. The overwhelming majority of the study participants were positive for anti-HAV (estimated seroprevalence, 75.3%; 95% confidence interval: 72.5–77.9%). The weighted seroprevalence estimates of HBsAg, anti-HCV and anti-HDV were 2.2% (1.5–3.3%), 3.8% (2.8–5.1%), and 0.40% (0.15–1.01%), respectively. Anti-HEV seropositivity was 3.3% (2.4–4.5%). Of the 33 HBsAg positive participants, five (15%) were anti-HDV positive. Our study confirms that Kyrgyzstan remains a high endemic country for hepatitis virus A and C infections. However, seroprevalences of HBV and HDV were lower than previously reported, and based on these data, the country could potentially be reclassified from high to (lower) intermediate endemicity. The observed anti-HEV seroprevalence resembles the low endemicity pattern characteristic of high-income countries.