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Introduction: Combating the epidemic of the novel coronavirus disease required decision-making at the state level and joining efforts of medical workers of all specialties. The experience of the Kaliningrad Region deserves special attention since this region is located in Central Europe and the first COVID-19 cases were imported here in March 2020. Objective: To assess COVID-19 epidemic manifestations and effectiveness of preventive measures at the regional level. Materials and methods: We performed a retrospective epidemiological analysis of COVID-19 incidence in the Kaliningrad Region from March 2020 to December 2022. All registered cases were confirmed by PCR or immunochromatography assay. The study included 193,259 cases, 1,879 fatal cases, 1,168 samples with the established SARS-CoV-2 genetic variant, and information on 693,627 people vaccinated against COVID-19. The data were analyzed in Microsoft Excel and WinPepi (version 11.65). Results: In 2020, the COVID-19 incidence rate in the Kaliningrad Region was lower than that in the Russian Federation while in the years 2021 and 2022 the regional rates were, on the opposite, higher than the respective national ones (p < 0.05). All age groups of the population were involved in the outbreak. Periodic rises in the incidence were associated with the replacement of the Delta variant of SARS-CoV-2 with Omicron. We established high efficacy of vaccination against COVID-19: incidence and mortality rates among the unvaccinated were significantly higher than those among vaccinated individuals (p < 0.05). Conclusion: Organization of uniform infection control measures has enabled timely interdepartmental managerial decision-making to control the epidemic. Russian regions have accumulated unique experience in implementing a set of preventive and anti-epidemic measures to combat the epidemic of the novel infection. © 2023, Federal Center for Hygiene and Epidemiology. All rights reserved.
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The aim of the study was to assess the seroprevalence to the SARS-CoV-2 nucleocapsid in the population of the Nizhny Novgorod region against the background of COVID-19. Materials and methods. The work was carried out according to a unified methodology developed by Rospotrebnadzor with the participation of the St. Pasteur. The selection of volunteers for the study was carried out by the method of questioning and randomization. The exclusion criterion was active COVID-19 infection at the time of the survey. A total of 2829 volunteers were surveyed, divided into seven age groups. Venous blood samples were taken from all volunteers from EDTA vacutainers. In the blood plasma, the content of specific IgG to the SARS-CoV-2 nucleocapsid was determined by the enzyme immunoassay. Results. The population level of immunity to SARS-CoV-2 among the surveyed volunteers was 8,4% (95% CI 7,4–9,5). The largest proportion of seroprevalent persons was found among children aged 1–6 years — 15,9% (95% CI 8,2–26,7), the smallest in the group of volunteers aged 18–29 years — 6,0% (95% CI 3,8–8,9). During 3-stage serological monitoring, the proportion of seroprevalent volunteers increased to 22,5% (95% CI 20,3–24,9)%, or almost 2 times from the initial level (p<0,05). of the population of the Semenovsky district (22,7% (95% CI 10,9–41,8)), the smallest — in the city of Dzerzhinsk (2,4% (95% CI 0,5–7,1)%) Among convalescents after COVID-19, specific antibodies were detected in 47,2% (95% CI 30,5–69,6), which is 5,6 times higher than the average for the population. Among those who had verified contact with patients, specific IgG were detected in 17,6% (95% CI 12,9–23,5), which is 2,1 times higher than the average for the population. Among asymptomatic persons who had a positive PCR result, 53,3% (95% CI 30,5–86,6) were seropositive, which is 6,3 times higher than the average for the population. Of 225 seropositive people, 188 (88,4% (95% CI 76,6–101,6)) had the disease asymptomatic. Conclusion. The relatively low proportion of seroprevalent persons among the population may indicate a significant risk of further development of the epidemic process caused by COVID-19 in the territory of the Nizhny Novgorod region. © 2021,HIV Infection and Immunosuppressive Disorders. All Rights Reserved.
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Introduction. The first pandemic in the 21st century, caused by the pathogenic representative of the coronavirus SARS-CoV-2, began in the Chinese city of Wuhan, where the first outbreak of coronavirus pneumonia was recorded in December 2019. The disease spread so quickly around the world that already on February 11, 2020, WHO was forced to declare a pandemic of the “coronavirus disease 2019” COVID-19. The first case of COVID-19 in the Stavropol Territory was registered on March 20, 2020, and three weeks later, starting from the 15th week of the year, a steady increase in the incidence began, which lasted until the 52nd week. During the study period, the incidence increased from 21.1 to 28.3 per hundred thousand of the population. Growth 1.3 times. Purpose: to determine the dynamics of population immunity among the population of the Stavropol Territory in 2020-2021. during the period of an epidemic increase in the incidence of COVID-19. Materials and methods. The SARS-CoV-2 study was carried out according to a unified methodology within the framework of the program for assessing the population immunity of the population of the Russian Federation, developed by Rospotrebnadzor with the participation of the St. Pasteur. In total, 2688 people were examined, divided into 7 age groups. In the examined individuals, the level of specific IgG to the SARS-CoV-2 nucleocapsid was determined by the enzyme immunoassay. Results. The level of seroprevalence among residents of the Stavropol Territory was 9.8%. The largest proportion of seropositive individuals was found in the age groups 1-6 and 7-13 years old (19.2% and 19.7%, respectively). Seroprevalence had no gender differences and ranged from 9.3% to 10.8%. When assessing the distribution of the proportion of seropositive persons in different geographic territories of the region, it was found that the maximum proportion was found in the Kochubeevsky district (23.1%), the minimum in Kislovodsk (7.7%). Among convalescents, the content of specific antibodies to SARS-CoV-2 was noted in 73.3%, which is 7.8 times higher than the average population level. When conducting seromonitoring in the 2nd half of 2020, a 10-fold increase in seroprevalence was recorded, accompanied by a decrease in incidence from the 5th week of 2021. Among asymptomatic volunteers in whom SARS-CoV-2 RNA was detected by the polymerase chain reaction, antibody titers to viruses were found in 78.6%, which corresponds to the seroprevalence of convalescents. The proportion of seropositive persons among those who have come into contact with CO-VID-19 patients was 16.4%, (1.8 times higher than the average for the population). Out of 262 seroprevalent volunteers, the asymptomatic form of SARS-CoV-2 was detected in 92% of the examined, which indicates a significant role of the number of asymptomatic forms of infection in the epidemic process of COVID-19. Conclusion. The results of assessing the population immunity of the population of the Stavropol Territory indicate that it has not yet reached the threshold level at which a decrease in the intensity of the COVID-19 epidemic process can be expected. © 2021 Interregional public organization Association of infectious disease specialists of Saint-Petersburg and Leningrad region (IPO AIDSSPbR). All rights reserved.
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The aim: to study the structure and dynamics of population immunity to SARSCoV-2 of the population of the Southern Regions of the Far East (SRFE): Khabarovsk, Primorsky Krai and Amur Region during the COVID-19 epidemic in 2020. Materials and methods. The work was carried out according to the program for assessing population immunity to SARS -CoV-2 of the population of the Russian Federation according to the methodology developed by the Rospotrebnadzor with the participation of the St. Petersburg Pasteur Institute. The study was approved by the ethical committee of the St. Petersburg Pasteur Institute. The selection of participants was carried out by a questionnaire method using cloud technologies. The volunteers were randomized by age by stratification into 7 age groups: 1–17, 18–29, 30–39, 40–49, 50–59, 60–69, 70+ years old. Territorial randomization consisted in limiting the engaging of volunteers – no more than 30 people from one enterprise. After the initialcross-sectionalstudy, a 3-stage seromonitoring was carried out, in which the same volunteers participated. Antibodies to the SARS-CoV-2 nucleocapsid were determined in peripheral blood serum by the enzyme immunoassay using an appropriate set of reagents produced by the State Scientific Center for Medical and Biological Sciences of the Rospotrebnadzor (Obolensk). Statistical analysis was performed using the Excel package. The confidence interval for the proportion was calculated using the A. Wald, J. Wolfowitz method with A. Agresti, B.A. Coull’s correction. The statistical significance of the differences was calculated online using a specialized calculator. The statistical significance of the differences was assessed with a probability of p < 0.05, unless otherwise indicated. Results. In a comparative analysis, the highest morbidity was observed in the Khabarovsk Territory, the lowest – in the Primorsky Territory. The level of seroprevalence among the population of the region was 19.6 % (95 % CI: 18.2–21.1) in the Khabarovsk Territory, 19.6 % (95 % CI: 18.1–21.2) in the Primorsky Territory19,6 % and 45,5 % (95 % CI: 43.7–47.3) in the Amur region. The highest seroprevalence was noted among 1–17 years old children, mainly due to the subgroup of 14–17-years-olds. The smallest proportion of seropositive was found among 40–49-year-olds in the Khabarovsk Territory (14.7 %, 95 % CI: 11.2–18.6), 18–28-year-olds in the Primorsky Territory (13.3 %, 95 % CI: 10.0–17.1) and 30–39-year-olds in the Amur Region (36.3 %, 95% CI: 31.7–41.6). No statistically significant dependence of seroprevalence on territorial and occupational factors has been established, with the exception of an increase in the proportion of seropositive medical workers in Primorsky Territory. In the process of 3-stage seromonitoring, a regular increase in the proportion of seropositive people was revealed in all SRFE. The resulting tendency is correctly describedby a second-order polynomial. Arelationship was revealed between the number of convalescents and persons in contact with them, which made it possible to calculate the base reproductive number (R0) in the range from 1.4 (Primorsky Territory) to 2.4 (Amur Region). Analysis of seroprevalent volunteers showed that the number of asymptomatic individuals varied from 94.1 % (95 % CI: 92.8–95.3) to 98.3 % (95 % CI: 98.8–99.2). This indicates that most of the volunteers had COVID-19 asymptomatically. Conclusions. A comparative study showed the prevalence of seroprevalence in the Amur Region compared with the Khabarovsk and Primorsky Territories. The relationship between the number of convalescents and persons in contact with them was noted. The value of the base R0 is calculated. It has been shown that more than 90 % of seropositive individuals in the COVID-10 SRFE were asymptomatic. © 2021 Scientific Centre for Family Health and Human Reproduction Problems. All rights reserved.
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AIM: To determine the level of SARS-CoV-2 seroprevalence among the Novosibirsk Region population against the background of the COVID-19 pandemic. MATERIAL AND METHODS: The work was carried out in 2 phases: 1) a cross-sectional cohort study performed 28.06- 15.07.2020; 2) longitudinal cohort 3-stage seromonitoring: 1st stage 28.06-15.07.2020; 2nd 14.09-04.10.2020; 3rd 10-30.12.2020 The work was carried out according to a unified methodology developed by Rospotrebnadzor with the participation of St-Petersburg Pasteur Institute, taking into account the recommendations of the WHO. IgG antibodies to the SARS-CoV-2 nucleocapsid protein were detected by ELISA using a kit of reagents produced by the SRCMSB (Obolensk) according to the manufacturer's instructions. Statistical analysis was performed using Microsoft Excel 2010 and other programs. RESULTS: The seroprevalence in the region's population was 9.1% (95% CI 8.0-10.2): maximum in children 14-17 years old (17.6%, 95% CI 12.3-23.9) and persons over 75 years (14.8%, 95% CI 11.4-18.8), minimum among persons 30-39 years old (4.9%, 95% CI 3.0-8.0). Increased rate was noted among the unemployed (15.4%, 95% CI 9.9-17.1) and other individuals (13.0%, 95% CI 8.6-18.5). Seroprevalence was 33.3% (95% CI 16.3-59.0) in COVID-19 convalescents and 19.0% (95% CI 13.9-25.0) in contact persons. More than 94.7% (95% CI 91.2-97.2) of seropositive individuals were asymptomatic. During the serological monitoring, seroprevalence increased from 7.4% (95% CI 6.2-8.9) at 1st stage 1 to 12.4% (95% CI 10.6-14.3) at 2nd , and 31% (95% CI 28.8-33.3) at 3rd stage. CONCLUSION: SARS-CoV-2 herd immunity has not reached the threshold level, this does not exclude exacerbation of the epidemic process.
Subject(s)
COVID-19/epidemiology , COVID-19/immunology , Immunity, Herd , Pandemics , SARS-CoV-2/immunology , Adolescent , Adult , Aged , Child , Female , Humans , Male , Middle Aged , Seroepidemiologic Studies , Siberia/epidemiologyABSTRACT
Purpose. Determination of the SARS-CoV-2 population humoral immunity among the population of the Krasnoyarsk Territory during the COVID-19 epidemic. Materials andmethods. The study was carriedoutas a partof projectfor assessing population immunity to SARS-CoV-2 among the population of Russian Federation using unified methodology developed by Rospotrebnadzor, with the participation of the Research Institute for Epidemiology and Microbiology named by Pasteur, and taking into account the recommendations of the WHO. The work involved 2907 volunteers, selected by the online survey and randomization by age and territory. All volunteers were divided into 7 age groups: 1–17, 18–29, 30–39, 40–49, 50–59, 60–69, 70 and older (70+), including a total 246–449 people. Population immunity testing was carried out during the formation of groups (1st stage), and then twice more, with the interval of 6–8 weeks. Serum was obtained from venous blood samples obtained from volunteers, in which antibodies to the SARS-CoV-2 nucleocapsid were determined by the enzyme immunoassay. The results were analyzed by methods of nonparametric statistics: median, interquartile range, rank correlation coefficient were calculated in the Excel statistical package. The confidence interval to seroprevalence indicators (95% CI) was calculated using the WinPepi statistical package (version 11.65). The statistical significance of the differences was assessed with a probability level of p ≤ 0.05. Results. The seroprevalence of the population of the Krasnoyarsk Territory during the 5-month period of seromonitoring had increased 3.3 times from 12.8% (95% CI 11.3–14.4) to 41.7% (95% CI 39.4–4.0), while the grouping by age had not revealedany peculiarities throughoutthe study. The trendtowards a decrease in the incidence was formedon the 6thweekof2021. The seroprevalence ofconvalescents after COVID-19 during the initial testing was 61.5% (95% CI 40,6–79.8), among those who were in contact with patients with COVID-19 or convalescents – 23.8% (95% CI 13.9–36.2) . Among the volunteers, 347 seropositive persons were identified, 324 of which were observed asymptomatic course. Conclusion. The structure of the population humoral immunity to SARS-CoV-2 of he population of the Krasnoyarsk Territory has been investigated. It was found that an increase in seroprevalence to 41.7% (95% CI 39.4–4.0) was accompanied by a decrease in morbidity. © 2021 Scientific Centre for Family Health and Human Reproduction Problems.
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Relevance. At the end of 2019, the world was confronted with a novel coronavirus (SARS-CoV-2), In January 2020, WHO declared an epidemic related to SARS-CoV-2, a health emergency of international importance, and in March characterized the spread of the world. diseases like a pandemic. Purpose of the study. Conduct a comparative analysis of the seroprevalence of the population of the Sverdlovsk and Chelyabinsk regions – the largest administrative territorial entities of the Middle and Southern Urals – against the backdrop of the COVID-19 pandemic. Materials and methods. The work was carried out under the program of the first stage of assessing the seroprevalence of the population of the Russian Federation according to a unified methodology developed by Rospotrebnadzor of the Russian Federation with the participation of the Saint Petersburg Pasteur Institute. The selection of participants was carried out by the method of questioning and randomization. The presence of antibodies to the SARS-CoV-2 nucleocapsid was determined in blood serum by the enzyme immunoassay. Results. Comparative analysis of the results showed that the incidence rate of COVID-19 in the Chelyabinsk region was consistently lower, and the seroprevalence at the first stage of the study was statistically significantly higher (p <0/05) than in the Sverdlovsk region. It was found that the incidence in both regions had a direct correlation with population density (r = 0.59;p <0.05). There were no differences between the compared areas in terms of seroprevalence among convalescents, people who had contact with COVID-19 patients, and asymptomatic volunteers with a positive PCR test. When analyzing seroprevalent volunteers in both regions, it was shown that the number of asymptomatic individuals varied within 94.4 ± 1.2% – 95.0 ± 0.95%. These data indicate that the majority of volunteers tolerated COVID-19 asymptomatically. Conclusions. A comparative study showed a statistically significant predominance of seroprevalence among the population of the Chelyabinsk region. It was found that an increase in seroprevalence at the population level was accompanied by a decrease in morbidity. Shown is a direct relationship between population density and the incidence rate. More than 90% of seropositive individuals in the compared areas showed asymptomatic course of coronavirus infection. © 2021, Numikom. All rights reserved.
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Purpose of the study. Determination of the level and structure of population immunity to SARS-CoV-2 among the population of the Murmansk region against the background of the incidence of COVID-19. Materials and methods. The study was carried out according to a unified method for determining the seroprevalence of the population, developed by Rospotrebnadzor with the participation of the St. Petersburg Pasteur Institute. A total of 3117 volunteers were examined, distributed into 7 age groups. The content of antibodies to SARS-CoV-2 was determined by ELISA using a set of reagents for analyzing human serum or plasma for the presence of specific immunoglobulins of class G to the nucleocapsid of the SARS-CoV-2 virus produced by the FBUN GNCPMiB Rospotrebnadzor (Obolensk) in accordance with the instructions for application. Results. The level of population immunity in the Murmansk region as a whole was 31,2%. The highest seroprevalence was found among children aged 1–6 and 7–13 years (35.6% and 44,1%, respectively), the lowest among the elderly population aged 60–69, as well as 70 and more years (20,4% and 20,9%, respectively). In the cities of the Murmansk region. the herd level of immunity varied from 19,6% (Kola city) to 46,1% (Kandalaksha city). It was not possible to find a reliable relationship between the incidence of the population of the cities of the Murmansk region and seroprevalence. The highest level of seroprevalence was noted among office workers (38,0%), the lowest among transport workers (19,5%). In the presence of contacts with patients with COVID-19, seropositivity increased 1,4 times compared to the average population value. The level of specific humoral immunity in convalescents after COVID-19 is 64,1%, which is 2,2 times higher than the average for half-day. The proportion of asymptomatic forms among seroprevalence volunteers was 89%. © 2021. All Rights Reserved.
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The novel coronavirus (SARS-CoV-2) pandemic, dubbed COVID-19, has become one of the most serious challenges for human populations in the vast majority of countries worldwide. Rapid spreading and increased mortality related to it required new approaches to manage epidemic processes on a global scale. One of such approaches was based on analyzing SARS-CoV-2 seroprevalence associated with COVID-19. Our aim was to summarize the results on assessing seroprevalence to the SARS-CoV-2 nucleocapsid antigen (Nc) in residents from 26 regions of the Russian Federation, carried out during the first wave of the COVID-19 epidemic. Materials and methods. Seroprevalence distribution was examined in 26 model regions of the Russian Federation according to the unified method developed by the Rospotrebnadzor with the participation of the Federal State Institution Saint Petersburg Pasteur Research Institute of Epidemiology and Microbiology. Such approach implied formation of a group of volunteer subjects in model geographic region who were tested by ELISA for anti-Nc serum antibody level in peripheral blood. Analyzed primary data obtained in separate regions were either accepted for publication or released. Results. The current paper finalizes the data obtained in all 26 regions of the Russian Federation. The total SARS-CoV-2 seroprevalence was 19.5 (10.0-25.6)% with the maximum and minimum value found in the Kaliningrad Region and the Republic of Crimea, respectively (50.2% vs. 4.3%). A pattern of age-related seroprevalence distribution indicates insignificant predominance of seroprevalence among subjects of 1-17 years old: 22.1 (13.1-31.8)%. Among COVID-19 convalescents positive for SARS-CoV Nc antibodies it reached 60.0 (40.0-73.3)%. The number of contact persons comprised 6285 subjects or 8.5% of total volunteer cohort, with the level of seroprevalence reaching up to 25.3 (17.95-35.8)%. A direct correlation was revealed between levels of seroprevalence in convalescent and contact volunteers. In addition, the reproductive number for SARS-CoV was calculated comprising 5.8 (4.3-8.5) suggesting that one convalescent subject can infect at least 4 healthy individuals. A high level of asymptomatic forms of COVID-19 among seropositive subjects was confirmed empirically comprising up to 93.6 (87.1-94.9)%. Conclusion. A single cross-sectional study performed during 2020 June-August timeframe allowed to assess pattern of sex- and age-related COVID-19 seroprevalence for general population in 26 Russian Federation regions. The data obtained may serve as a basis for the longitudinal cohort investigation with serial subject sampling. The timing and duration of study will be determined by dynamics of ongoing COVID-19 epidemic.
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By August 2020, more than 850000 cases of new coronavirus infection (COVID-19) caused by SARS-CoV-2 were confirmed in the Russian Federation, with the Rostov Region as one of the ten most affected regions in Russia. The spread of the disease is largely determined by the state of population immunity in a certain area. Our research focuses on specific humoral immune response and estimates the level of herd immunity to SARS-CoV-2 virus among the population of the Rostov Region. Materials and methods. The study involved 3,048 people;the volunteers participating in the study were divided into seven age groups. The content of antibodies to SARS-CoV-2 was determined applying ELISA using a kit for the analysis of human serum or blood plasma for the presence of specific IgG to the nucleocapsid of the SARS-CoV-2 virus, manufactured by the State Scientific Center of Applied Microbiology and Biotechnology (Obolensk) in accordance with the instructions for use. Results and discussion. The assessment of seroprevalence to SARS-CoV-2 in the Rostov Region showed that the proportion of people positive for IgG to the new coronavirus was 16.5 %, the range of seropositive individuals in the general population was between 13.9 % and 19.1 % (p<0.05). There were no significant gender differences in the degree of seroprevalence with a positive result registered in 16.6 % of women and 16.5 % of men. A high level of humoral immunity to SARS-CoV-2 was established in individuals aged 1–17 against the background of low incidence rates, which may indicate the dominance of asymptomatic forms of the disease in this age group. The highest level of seropositivity was found in preschool children (33.6 %), students (29.3 %), employees (17.3 %), and education professionals (15.3 %). © 2020 Russian Research Anti-Plague Institute. All rights reserved.
ABSTRACT
In late 2019, there were reports of an outbreak of infection caused by a new strain of beta coronavirus SARSCoV-2, the WHO identified the disease as coronavirus disease 2019 (COVID-19). In Tatarstan, the first case of COVID-19 was diagnosed on March 16, 2020, it was an imported case from France. The period of increase in the incidence lasted during the 12th to the 19th week, when the highest rate was recorded, amounting to 16.7 per 100 thousand population. Subsequently, a statistically significant decrease in the incidence was noted. Seroprevalence study was conducted at week 27 (8th week of decline of morbidity).The purpose of the seroepidemiological study was to measure the level and to identify the structure of herd immunity against the SARS-CoV-2 virus among the population of the Republic of Tatarstan during the rapid spread of the COVID-19 outbreak.Materials and methods. The selection of volunteers for the study was carried out by the method of questionnaires and randomization by random sampling. The exclusion criterion was active COVID-19 infection at the time of the survey. 2,946 people were examined for the presence of specific antibodies to SARS-CoV-2. The age of the surveyed volunteers ranged from 1 year to 70 years and older.Results. The results of the study showed that in the Republic of Tatarstan during the period of COVID-19 incidence, there was a moderate seroprevalence to SARS-CoV-2, which amounted to 31.3%, against the background of a high frequency (94.5%) of asymptomatic infection in seropositive individuals who did not have a history of past COVID-19 disease, positive PCR result and ARVI symptoms on the day of the examination. The maximum indicators of herd immunity were established in children aged 7-13 years (42.0%), children 14-17 years old (40.3%), with a simultaneous decrease in seroprevalence in persons aged 70 and older (24.0%). In different regions of the Republic of Tatarstan, there was a wide variation in seropositivity results from the minimum in the Zainsky district (8.6%) to the maximum in the Arsky district (74.3%). In 21 out of 38 surveyed districts, the results were unrepresentative due to the small sample size. In COVID-19 convalescents, antibodies are produced in 83.3% of cases. In persons with a positive result of the PCR analysis carried out earlier, antibodies were detected in 100% of cases. Among the volunteers who had contact with patients with COVID-19, the proportion of seropositive is 37%Conclusion. The dynamics of seroprevalence among the population of the Republic of Tatarstan can be qualified as positive, the results obtained can be used to develop a forecast for the development of the epidemiological situation, as well as to plan measures for specific and non-specific prevention of COVID-19. В конце 2019 г. появились сообщения о вспышке инфекции, вызванной новым штаммом beta-коронавируса SARS-CoV-2, заболевание ВОЗ определила как coronavirus disease 2019 (COVID-19). В Республике Татарстране первый случай COVID-19 был диагностирован 16.03.2020 г., это был завозной случай из Франции. Период нарастания заболеваемости продолжался с 12-й по 19-ю неделю, когда был зарегистрирован самый высокий показатель, составивший 16,7 на 100 тыс. населения. В дальнейшем отмечалось статистически значимое снижение заболеваемости. Исследование серопревалентности было проведено на 27-й неделе (8-я неделя снижения заболеваемости)Целью проведенного сероэпидемиологического исследования было определение уровня и структуры популяционного иммунитета к вирусу SARS-CoV-2 среди населения Республики Татарстан в период распространения COVID-19.Материалы и методы. Отбор волонтеров для исследования проводили методом анкетирования и рандомизации путем случайной выборки. Критерием исключения была активная инфекция COVID-19 в момент анкетирования. На наличие специфических антител к SARS-CoV-2 обследовано 2946 человек. Возраст обследованных добровольцев варьировал от 1 года до 70 лет и старше.Результаты. Результаты исследования показали, что в Республике Татарстан в период заболеваемости COVID-19 наблюдалась умеренная серопревалентность к SARS-CoV-2, составившая 31,3%, на фоне высокой частоты (94,5%) бессимптомной инфекции у серопозитивных лиц, не имевших в анамнезе перенесенного заболевания COVID-19, положительного результата ПЦР и симптомов ОРВИ в день обследования. Максимальные показатели коллективного иммунитета установлены у детей 7-13 лет (42,0%), детей 14-17 лет (40,3%) при одновременном снижении серопревалентности у лиц в возрасте 70 лет и старше (24,0%). В разных регионах Республики Татарстан наблюдалось широкое варьирование показателей серопозитивности от минимального в Заинском районе (8,6%) до максимального в Арском районе (74,3%). В 21 районе из 38 обследованных результаты были нерепрезентативны из-за малого числа наблюдений. У реконвалесцентов COVID-19 антитела вырабатываются в 83,3% случаев. У лиц с позитивным результатом ПЦР-анализа, проведенного ранее, антитела выявлялись в 100% случаев. Среди волонтеров, имевших контакты с больными COVID-19, доля серопревалентных 37%.Вывод. Динамику серопревалентности среди населения Республики Татарстан можно квалифицировать как позитивную. Полученные результаты могут быть использованы для разработки прогноза развития эпидемиологической ситуации, а также планирования мероприятий по специфической и неспецифической профилактике COVID-19.
ABSTRACT
Introduction. The COVID-19 pandemic was announced by WHO in February 2020. In the Kaliningrad region, the first case (imported) was registered in early March 2020, the beginning of the epidemic increase fell on the 14th week. 2020, and the peak incidence was reached in the 22nd week of the year, after which there was a steady decrease in the number of cases. The study of population immunity was carried out at the 32nd week during the period of the lowest level of intensity of the epidemic process. Purpose of the study. Assessment of the assessment of the level of population immunity to the SARS-CoV-2 virus among the population of the Kaliningrad region during the period of the epidemic incidence of the population of COVID-19. Materials and methods. The study was carried out as part of the first stage of the Rospotrebnadzor program to assess population immunity to SARS-CoV-2 among the population of the Russian Federation. The selection of volunteers for the study was carried out by a questionnaire survey and subsequent randomization. The analysis includes the results of a survey of 2675 people. The number of volunteers in age groups ranged from 314 to 493 people. The results obtained were processed by the methods of variation statistics. Results. The results obtained showed that the average seroprevalence in the population was 50.2%, while the highest seroprevalence was found in the child age group 1-17 years (66.9%) and among persons aged 18-29 (57.0). No significant gender differences were found (men – 48,3 ± 1,6%, women – 51,1 ± 1,1%). The distribution of the proportion of seropositive people in the settlements of the region varied from 33,9% to 59.6%. The largest share of seroprevalence in the representative samples was found among people engaged in art / creativity (55,3%), the smallest – among educational workers (42,0%). Among COVID-19 convalescents, the level of humoral immunity reached 94,6%. Most of the seropositive volunteers (95,2%) did not have any symptoms of COVID-19, that is, they belonged to the category of asymptomatic carriers. Output. The results of a survey of a representative cohort of volunteers in the Kaliningrad region showed that they are characterized by a high level of population immunity, which makes it possible to expect a decrease in. © 2021 Interregional public organization Association of infectious disease specialists of Saint-Petersburg and Leningrad region (IPO AIDSSPbR). All rights reserved.
ABSTRACT
The first case of COVID-19 was diagnosed in St. Petersburg on March 2, 2020;the period of increase in the incidence lasted for 10 weeks, the maximum rates were recorded in mid-May, and subsequently there was a statistically significant decrease in the incidence. Objective: to determine the level and structure of community immunity to SARS-CoV-2 among the population of St. Petersburg during the period of intensive spread of COVID-19. Materials and methods. Selection of volunteers for the study was carried out through interviewing and randomization. The exclusion criterion was active COVID-19 infection at the time of the survey. 2713 people aged 1 to 70 years and above were examined for the presence of specific antibodies to SARS-CoV-2. Antibodies were detected by enzyme immunoassay. Results and discussion. Studies have shown that in St. Petersburg, in the active phase of COVID-19 epidemic, there was a moderate seroprevalence to SARS-CoV-2, which amounted to 26 %, against the background of a high frequency (84.5 %) of asymptomatic infection in seropositive individuals who did not have a history of COVID-19 disease, positive PCR result and ARI symptoms on the day of examination. The maximum indicators of herd immunity were established in children 1–6 years old (31.1 %), 7–13 years old (37.7 %) and people over 70 years old (30.4 %). Differences in the level of seroprevalence in the age groups of 18–49 years are statistically significant. The highest level of seroprevalence was found among the unemployed (29.7 %), healthcare workers (27.1 %), education sector (26.4 %) and business sector personnel (25 %). In convalescents, COVID-19 antibodies are produced in 75 % of cases. In individuals with positive result of PCR analysis carried out earlier, antibodies are detected in 70 % of the cases. The results of the study of herd immunity to SARS-CoV-2 are essential to forecast the development of the epidemiological situation, as well as to plan measures for specific and non-specific prevention of COVID-19. © 2020 Russian Research Anti-Plague Institute. All rights reserved.
ABSTRACT
The first case of COVID-19 was registered in the Leningrad Region on March 13, 2020. The period of increasing intensity of the epidemic process lasted 8 weeks. One month after reaching the maximum incidence rate, a study was organized to determine seroprevalence to COVID-19 among the population of the Region. Objective of the study was to determine the level and structure of community immunity to SARS-CoV-2 virus in the population of the Leningrad Region in the period of intensive COVID-19 transmission. Materials and methods. The work was carried out within the framework of the Rospotrebnadzor project on assessment of community immunity to the SARS-CoV-2 virus in the population of the Russian Federation. The content of antibodies to SARS-CoV-2 was determined applying ELISA using a kit for the analysis of human serum or blood plasma for the presence of specific IgG to the nucleocapsid of the SARS-CoV-2 virus, manufactured by the State Scientific Center of Applied Microbiology and Biotechnology (Obolensk) in accordance with the instructions for use. Results and discussion. The study has showed that the herd immunity of the population of the Leningrad Region was 20.7 %. The maximum level has been established in children 1–6 years old (42.3 %) and people over 70 years old (29.0 %). The highest level of seropositivity, except for children and older people, was found among the unemployed (25.1 %). The lowest level of seroprevalence was detected in civil servants (12.8 %) and military personnel (16.7 %). It has been shown that the risk of infection increases by 1.5 times in case of contacts with COVID-19 patients. After exposure to COVID-19 virus, antibodies are produced in 82.1 % of the cases. In individuals with a positive PCR test result obtained earlier, antibodies are detected in 82.8 % of cases. The share of asymptomatic forms among seropositive residents of the Leningrad Region was 86.9 %. The results of assessing the herd immunity to SARS-CoV-2 in the population of the Leningrad Region indicate that during the period of intensive COVID-19 transmission, an average level of seroprevalence was formed. A significant proportion of asymptomatic forms of infection characterizes the high intensity of the latently developing epidemic process. The results obtained should be taken into account when organizing preventive measures, including vaccination, and predicting morbidity rates. © 2020 Russian Research Anti-Plague Institute. All rights reserved.
ABSTRACT
Objective of the seroepidemiological study was to determine the level and structure of herd immunity to SARS-CoV-2 among the population of the Irkutsk Region during the period of an increase in the incidence of COVID-19. Materials and methods. The content of antibodies to SARS-CoV-2 was determined by ELISA applying a reagent panel “ELISA anti-SARS-Cov-2 IgG” produced by the State Scientific Center of Applied Microbiology and Biotechnology (Obolensk). Results and discussion. The investigation has revealed that the herd immunity of the total population of Irkutsk Region amounted to 5.8 %. The greatest share of seropositive persons was among the children aged 14–17 (13.8 %) and 1–6 (11.8 %). It has been established that the risk of infection increases by 3.1 times in case of contact with COVID-19 patients. After exposure to COVID-19, antibodies were produced in 56.5 % of the cases. The share of asymptomatic forms among seropositive residents of the Irkutsk Region reached 81.2 %. Consequently, during the chosen period of increased COVID-19 incidence among the population of Irkutsk Region low level of seroprevalence was formed. A significant proportion of asymptomatic forms of infection characterize high intensity of the latently developing epidemic process. The results obtained can be used when organizing preventive measures, including vaccination, and for forecasting morbidity rates. © 2020 Russian Research Anti-Plague Institute. All rights reserved.