scholarly journals Assessment of the Herd Immunity to SARS-CoV-2 among the Population of the Leningrad Region during the COVID-19 Epidemic

2020 ◽  
pp. 114-123
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Mel’nikova ◽  
O. A. Historik ◽  
O. S. Mosevich ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Significant Proportion ◽  
Maximum Level ◽  
Leningrad Region ◽  
Scientific Center ◽  
Epidemic Process ◽  
First Case ◽  
Applied Microbiology ◽  
Instructions For Use ◽  
The Unemployed

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. 

scholarly journals Experience in Studying Seroprevalence to SARS-CoV-2 Virus in the Population of the Irkutsk Region during COVID-19 Outbreak

2020 ◽  
pp. 106-113
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Mel’nikova ◽  
S. V. Balakhonov ◽  
M. V. Chesnokova ◽  
...  
Keyword(s):  
High Intensity ◽  
Total Population ◽  
Preventive Measures ◽  
Herd Immunity ◽  
Significant Proportion ◽  
Risk Of Infection ◽  
Scientific Center ◽  
Low Level ◽  
Irkutsk Region ◽  
Applied Microbiology

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. 

scholarly journals Characteristics of the Herd Immunity to SARS-CoV-2 in Residents of the Saratov Region under COVID-19 Epidemic

2021 ◽  
pp. 106-116
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Mel’nikova ◽  
V. V. Kutyrev ◽  
O. I. Kozhanova ◽  
...  
Keyword(s):  
Clinical Symptoms ◽  
Herd Immunity ◽  
Age Groups ◽  
Pcr Analysis ◽  
Maximum Increase ◽  
Scientific Center ◽  
Saratov Region ◽  
Infected People ◽  
First Case ◽  
Coronavirus Infection

The global community is experiencing one of the largest infectious disease outbreaks in the 21st century. In the Saratov Region, the first case of new coronavirus infection was confirmed on March 19, 2020.The maximum increase in cases was noted between May 15 and June 30, during that time the total number of infected people in the region increased from 1526 to 6444. Since July 2020, a stable incidence level of new coronavirus infection has been observed in the Saratov Region, without a steady decline.The aim of the study was to assess the status of population immunity to the SARS-CoV-2 virus among residents of Saratov and the Saratov Region under the COVID-19 epidemic.Materials and methods. In the period from June 23 to July 26, 2020, a serological study of blood samples from 3372 volunteers of different age groups was conducted. The content of antibodies to SARS-CoV-2 was determined by ELISA using a set of reagents “ELISA anti-SARS-CoV-2 IgG” produced by the State Scientific Center of Applied Microbiology and Biotechnology of the Rospotrebnadzor (Russia).Results and discussion. In general, the incidence of COVID-19 in the Saratov Region is taking place against the background of moderate seroprevalence to the SARS-CoV-2 virus, accompanied by a high incidence of non-apparent (asymptomatic) forms of the infectious process. The absence of clinical symptoms of the disease, in the context of the limited use of methods for determining the RNA of the SARS-CoV-2 virus in PCR (11 % of the region’s population) makes it difficult to assess the real spread of the virus in the population and to establish the timing of the formation of persistent herd immunity. A low rate of antibody response among individuals with a positive result of PCR analysis, as well as among volunteers who had an infection in May, June 2020, indicates a weak formation of the immune response, or the prevalence of individuals reacting mainly by activating the cellular link of the immune system in the population. The obtained results, although they need to be explained in a number of respects, can be applied to the organization of preventive measures, including vaccination, in the region. 

scholarly journals Herd Immunity to SARS-CoV-2 among the Population in Saint-Petersburg during the COVID-19 Epidemic

2020 ◽  
pp. 124-130 ◽  
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Mel’nikova ◽  
N. S. Bashketova ◽  
R. K. Fridman ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Age Groups ◽  
Active Phase ◽  
Asymptomatic Infection ◽  
Exclusion Criterion ◽  
Pcr Analysis ◽  
First Case ◽  
History Of ◽  
The Unemployed ◽  
Selection Of

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. 

scholarly journals Characteristic of herd immunity among the population of Stavropol region amid the COVID-19 epidemic

2021 ◽  
Vol 13 (4) ◽  
pp. 79-89
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Melnikova ◽  
V. S. Smirnov ◽  
L. V. Lyalina ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Age Groups ◽  
Population Level ◽  
Fold Increase ◽  
Disease Spread ◽  
Steady Increase ◽  
Epidemic Process ◽  
Population Immunity ◽  
First Case ◽  
Asymptomatic Volunteers

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 COVID-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. 

scholarly journals The seroprevalence of SARS-CoV-2 among residents of the Khabarovsk Krai during the COVID-19 epidemic

2021 ◽  
Vol 98 (1) ◽  
pp. 7-17
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Melnikova ◽  
O. E. Trotsenko ◽  
T. A. Zaitseva ◽  
...  
Keyword(s):  
Large Scale ◽  
Herd Immunity ◽  
Age Groups ◽  
Maximum Level ◽  
Fold Increase ◽  
Incidence Rates ◽  
High Rate ◽  
Slow Increase ◽  
Khabarovsk Krai ◽  
Epidemic Process

Introduction. The coronavirus disease (COVID-19) pandemic was announced by WHO in February 2020. In the Khabarovsk Krai, the first three cases of the disease were diagnosed on March 19, 2020, these cases were imported from Argentina (transit through Italy). The epidemic process of COVID-19 in the Khabarovsk Krai is characterized by a slow increase in the incidence. During the period of time when the SARS-CoV-2 seroprevalence study was conducted the incidence rates varied from 35.9 to 39.1 per 100 thousand population. Within the next 5 weeks the incidence continued to increase, the maximum level was 67.3 per 100 thousand population. A statistically significant decrease in the incidence is noted in the first decade of August. The study of the SARS-CoV-2 seroprevalence among residents of the region was carried out from June 9 to June 21, 2020 during the period of increasing intensity of the epidemic process of COVID-19 infection.Aim. To determine the level and structure of herd immunity to SARS-CoV-2 virus among the population of the Khabarovsk Krai during the period of intensive spread of COVID-19.Materials and methods. The study was conducted as a part of the first stage of a large-scale Rospotrebnadzor project to assess the herd immunity to SARS-CoV-2 virus among the population of the Russian Federation, taking into consideration the protocol recommended by WHO. The selection of volunteers for the study was carried out by the method of questionnaires and randomization by random sampling. The results of a survey of 2675 individuals were included into analysis. The number of volunteers in all age groups was similar.Results. The results of the study showed that the herd immunity to SARS-CoV-2 in the total population of the Khabarovsk Krai was 19.6%. The maximum level of herd immunity was observed in children 14–17 years old (34.4%), children 7–13 years old (24.8%), and people over 70 years (22.6%). The highest level of seropositivity, except for the children and the elderly, was found among educational workers (26.7%). The lowest level of seropositivity was found in the military (8.7%) and the unemployed (8.3%). There were no statistically significant differences in the level of seroprevalence between men and women.Conclusions. The results of the seroepidemiological study demonstrated that in the Khabarovsk Krai, the presence of the contacts with COVID-19 patients is associated with the 1.4-fold increase in the likelihood of the seroconversion. Antibodies were detected in 58.9% of the past COVID-19 cases. In individuals with the previous positive PCR test result, antibodies were detected in 50% of cases. A high rate of asymptomatic infection, up to 93.7%, was observed among seropositive volunteers.

Collective immunity to SARS-CoV-2 of Moscow residents during the COVID-19 epidemic period

2020 ◽  
Vol 18 (4) ◽  
pp. 8-16
Author(s):  
A.Yu. Popova ◽  
◽  
E.B. Yezhlova ◽  
A.A. Melnikova ◽  
E.E. Andreeva ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Age Groups ◽  
Asymptomatic Infection ◽  
Administrative District ◽  
Cultural Workers ◽  
Population Immunity ◽  
The North ◽  
First Case ◽  
Epidemic Period ◽  
Structure Of Population

The coronavirus disease pandemic (COVID-19) was announced by WHO in February 2020. In Moscow, the first case of the disease was detected on March 2, 2020 in a man who arrived from Italy. Two weeks after the first case, there was an exponential increase in the number of cases. The incidence peaked in the 19th week of the year, followed by a steady decline, lasting 16 weeks. Objective. To investigate the level and structure of population immunity to the SARS-CoV-2 virus among the population of Moscow against the background of the incidence of COVID-19. Patients and methods. The study of population immunity of Moscow residents to SARS-CoV-2 was carried out in the period from July 1, 2020 to July 30, 2020 against the background of stabilization of the incidence rate. The work was conducted as part of the first stage of the Rospotrebnadzor project to assess population immunity to the SARS-CoV-2 virus among the population of the Russian Federation, taking into account the protocol recommended by WHO. Volunteers for the study were selected by the method of questioning and randomization. The results of the survey of 2688 people were included in the analysis. The number of volunteers in all age groups was 384–385 people. The content of specific IgG to the SARS-CoV-2 nucleocapsid was determined by the enzyme-linked immunosorbent assya using a kit produced by FBIS SRCAMB according to the manufacturer's instructions. Results. During the survey of volunteers it was found that the share of seroprevalent residents of Moscow was 22.1%. By age groups, the highest proportion of seroprevalent was found among children aged 14–17 years (44.6%), the lowest (15.9%) – among people aged 18–29 years. Seroprevalence had no gender differences. The lowest level of herd immunity was revealed in the North-Western Administrative District (16.8%), the highest – in the South-Eastern Administrative District, as well as in the Troitsky and Novomoskovsky Administrative Districts of Moscow (in both, 24.1%). The smallest number of seropositive persons was among cultural workers (5.8%), the largest – among medical workers (27.0%). In the presence of contacts with patients with COVID-19, the probability of seroconversion increases by 1.5 times, and among convalescing persons COVID-19 antibodies were detected in 60.0% of cases. The proportion of people with asymptomatic infection among seropositive residents was 82.4%. Conclusion. The results obtained make it possible to characterize the population immunity of Moscow residents and are essential for the planning and implementation of anti-epidemic measures during the incidence of COVID-19. Key words: coronaviruses, SARS-CoV-2, seroprevalence, population, COVID-19

scholarly journals COVID-19 Vaccinations: A Comprehensive Review of Their Safety and Efficacy in Special Populations

Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1097
Author(s):  
Zhipeng Yan ◽  
Ming Yang ◽  
Ching-Lung Lai
Keyword(s):  
Decision Making ◽  
Herd Immunity ◽  
Significant Proportion ◽  
Special Populations ◽  
Safety And Efficacy ◽  
Comprehensive Review ◽  
Vaccination Programs ◽  
Vaccination Decision ◽  
Immunocompromised State ◽  
To Receive

COVID-19 has been spreading worldwide since late 2019. There is no definitive cure to date. Global vaccination programs are urgently required to confer herd immunity, reducing the incidence of COVID-19 infections and associated morbidity and mortality. However, a significant proportion of special populations are hesitant to receive vaccination due to their special conditions, namely, age (pediatrics and geriatrics), immunocompromised state, autoimmune diseases, chronic cardiovascular and pulmonary conditions, active or treated cancers, and pregnancy. This review aims to evaluate the existing evidence of COVID-19 vaccinations on these special populations and to provide clues to guide vaccination decision making to balance the benefits and risks of vaccinations.

scholarly journals RISK APPETITE ASSESSMENT FRAMEWORK

2020 ◽  
pp. 35-46
Author(s):  
Iryna Fedulova ◽  
Nataliia Skopenko
Keyword(s):  
Maximum Level ◽  
Risk Tolerance ◽  
Qualitative Assessment ◽  
Managerial Decision ◽  
Advantages And Disadvantages ◽  
Business Goals ◽  
Qualitative Approaches ◽  
First Case ◽  
Risk Appetite ◽  
Risk Event

he adoption of any managerial decision within the company happens in the presence of risks. Against this background, it is vital to determine whether the risk is acceptable for achieving the objectives. In the article the essence of risk appetite, risk tolerance and risk capacity is considered. Differences between risk capacity, risk appetite and risk tolerance are defined. Risk appetite reflects the level of losses that the company is willing to accept in order to achieve its strategic objectives. In contrast, risk tolerance is related to the acceptance of the outcomes of specific identified risk events and is defined as readiness for certain risk event. Risk capacity is the maximum level of risk that an organization is able to accept for achieving its business goals, taking into account the current level of resources, its capital structure and access to markets. An important part of identifying the risk appetite for the company is a description of advantages and disadvantages of existing methods of its assessment. Quantitative and qualitative approaches to determining risk appetite are considered. In the first case, the absolute value of possible risk or its relative value is established. In this case, the risk appetite is determined depending on organizational objectives. These objectives may determine the achievement of the planned financial indicators, compliance with financial regulations and other indicators of the company. Qualitative assessment of risk appetite is used when the risk cannot be quantified. In this case, the risk appetite is presented in a descriptive way. It is important to define the risk appetite including all aspects of the enterprise activity in the context of certain strategic goals of its development. Breaching the risk tolerance threshold should serve as a red alert for management. In such a case, it is important to reduce the risk position.

scholarly journals Herd immunity to SARS-COV-2 in the population of the Southern regions of the Far East of Russia

2021 ◽  
Vol 6 (5) ◽  
pp. 253-273
Author(s):  
A. Yu. Popova ◽  
V. S. Smirnov ◽  
E. B. Ezhlova ◽  
A. A. Melnikova ◽  
O. E. Trotsenko ◽  
...  
Keyword(s):  
Statistical Significance ◽  
Herd Immunity ◽  
Far East ◽  
Amur Region ◽  
Reproductive Number ◽  
Pasteur Institute ◽  
Scientific Center ◽  
Cross Sectional ◽  
Population Immunity ◽  
The Far East

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 initial cross-sectional study, 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-yearolds 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 described by a second-order polynomial. A relationship 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.

scholarly journals Estimating the impact of interventions against COVID-19: from lockdown to vaccination

2021 ◽  
Author(s):  
James Thompson ◽  
Stephen Wattam
Keyword(s):  
Spatial Clustering ◽  
Herd Immunity ◽  
Contact Tracing ◽  
Agent Based Model ◽  
Seir Model ◽  
Agent Based ◽  
Resident Population ◽  
First Case ◽  
Equivalent Equation ◽  
The Impact

AbstractCoronavirus disease 2019 (COVID-19) is an infectious disease of humans caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the first case was identified in China in December 2019 the disease has spread worldwide, leading to an ongoing pandemic. In this article, we present a detailed agent-based model of COVID-19 in Luxembourg, and use it to estimate the impact, on cases and deaths, of interventions including testing, contact tracing, lockdown, curfew and vaccination.Our model is based on collation, with agents performing activities and moving between locations accordingly. The model is highly heterogeneous, featuring spatial clustering, over 2000 behavioural types and a 10 minute time resolution. The model is validated against COVID-19 clinical monitoring data collected in Luxembourg in 2020.Our model predicts far fewer cases and deaths than the equivalent equation-based SEIR model. In particular, with R0 = 2.45, the SEIR model infects 87% of the resident population while our agent-based model results, on average, in only around 23% of the resident population infected. Our simulations suggest that testing and contract tracing reduce cases substantially, but are much less effective at reducing deaths. Lockdowns appear very effective although costly, while the impact of an 11pm-6am curfew is relatively small. When vaccinating against a future outbreak, our results suggest that herd immunity can be achieved at relatively low levels, with substantial levels of protection achieved with only 30% of the population immune. When vaccinating in midst of an outbreak, the challenge is more difficult. In this context, we investigate the impact of vaccine efficacy, capacity, hesitancy and strategy.We conclude that, short of a permanent lockdown, vaccination is by far the most effective way to suppress and ultimately control the spread of COVID-19.

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