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 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 Herd immunity of sars-cov-2 among the population of Kalinigrad region amid the COVID-19 epidemic

2021 ◽  
Vol 12 (5) ◽  
pp. 62-71
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Melnikova ◽  
E. A. Babura ◽  
O. P. Mikheenko ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Age Groups ◽  
Population Immunity ◽  
First Case ◽  
The Russian Federation ◽  
Kaliningrad Region ◽  
High Level ◽  
Representative Cohort ◽  
Representative Samples ◽  
Selection Of

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.

scholarly journals Distribution of SARS-CоV-2 seroprevalence among residents of the Republic of Tatarstan during the COVID-19 epidemic period

2021 ◽  
Vol 97 (6) ◽  
pp. 518-528
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Melnikova ◽  
M. A. Patyashina ◽  
E. P. Sizova ◽  
...  
Keyword(s):  
Small Sample Size ◽  
Herd Immunity ◽  
Asymptomatic Infection ◽  
Small Sample ◽  
Exclusion Criterion ◽  
Pcr Analysis ◽  
Imported Case ◽  
First Case ◽  
Epidemic Period ◽  
The Republic

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.

The structure of seroprevalence to the SARS-CoV-2 virus among residents of the Moscow Region during the period of epidemic incidence of COVID-19

2020 ◽  
Vol 18 (4) ◽  
pp. 17-26
Author(s):  
A.Yu. Popova ◽  
◽  
E.B. Ezhlova ◽  
A.A. Melnikova ◽  
O.M. Mikailova ◽  
...  
Keyword(s):  
Large Scale ◽  
Medical Center ◽  
Age Groups ◽  
Maximum Level ◽  
Test System ◽  
Moscow Region ◽  
Pcr Analysis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Population Immunity ◽  
First Case

A pandemic of the disease caused by the SARS-CoV-2 virus (hereinafter referred to as COVID-19) was announced by WHO in February 2020. In the Moscow Region (MR), the first case of the disease was detected on March 7, 2020 in a woman who arrived from Switzerland. Four weeks later, a rapid rise began, the peak of which fell on the 20th week (May 11, 2020 – May 17, 2020), which was replaced by a gradual steady decline that lasted for 13 weeks. Objective. To determine the level and structure of population immunity to the SARS-CoV-2 virus among the population of the Moscow Region between June 22, 2020 and July 11, 2020. Patients and methods. A serological study of seroprevalence among residents of MR to COVID-19 was carried out from June 22, 2020 till July 11, 2020 during the period of a steady decline in the incidence. The work was conducted as part of the first stage of the large-scale Rospotrebnadzor program to assess population immunity to the COVID-19 virus among the population of the Russian Federation. Volunteers for the study were selected by the method of questioning and randomization. The analysis included the results of a survey of 2688 people. The number of volunteers in all age groups was equal. The content of specific IgG to the COVID-19 nucleocapsid was determined by the enzyme-linked immunosorbent assay using a test system manufactured by the FBIS SRCAMB according to the manufacturer's instructions. Results. The results of the study showed that the collective immunity of the total population of the Moscow Region was 21.0%. The maximum level of population immunity was established in children aged 14–17 years (30.7%) and 1–6 years old (25.2%). There were no statistically significant differences in the level of seroprevalence between men and women. As a result of seroepidemiological research, it was shown that in the medical center, in the presence of contacts with patients with COVID-19, the risk of infection increases by 2.5 times. After infection with COVID-19, antibodies were detected in 78.7% of cases. In persons with a positive result of the PCR analysis obtained earlier, antibodies were detected in 82.8% of cases. A high proportion of asymptomatic infection among seropositive volunteers was found, which amounted to 83.4%. Key words: coronaviruses, SARS-CoV-2, incidence, seroprevalence, the Moscow Region, population, COVID-19

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 Assessment of Population Immunity to SARS-CoV-2 Virus in the Rostov Region

2021 ◽  
pp. 117-124
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Mel’nikova ◽  
A. K. Noskov ◽  
E. V. Kovalev ◽  
...  
Keyword(s):  
Herd Immunity ◽  
Age Groups ◽  
Incidence Rates ◽  
The State ◽  
Scientific Center ◽  
Education Professionals ◽  
Humoral Immune ◽  
Population Immunity ◽  
Rostov Region ◽  
High Level

By August 2020, more than 850000 cases of new coronavirus infection (COVID-19) caused by SARSCoV-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 %). 

scholarly journals Structure of herd immunity to SARS-COV-2 in the Krasnoyarsk region population in the COVID-19 epidemic

2021 ◽  
Vol 6 (3) ◽  
pp. 227-238
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Melnikova ◽  
V. S. Smirnov ◽  
L. V. Lyalina ◽  
...  
Keyword(s):  
Humoral Immunity ◽  
Online Survey ◽  
Statistical Significance ◽  
Venous Blood ◽  
Herd Immunity ◽  
Age Groups ◽  
Rank Correlation ◽  
Population Immunity ◽  
Formation Of Groups

Purpose. Determination of the SARS-CoV-2 population humoral immunity among the population of the Krasnoyarsk Territory during the COVID-19 epidemic.Materials and methods. The study was carried out as a part of project for 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 revealed any peculiarities throughout the study. The trend towards a decrease in the incidence was formed on the 6th week of 2021. The seroprevalence of convalescents 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.

scholarly journals Humoral immunity to SARS-CoV-2 among the population of Murmansk region amid COVID-19 epidemic

2021 ◽  
Vol 13 (1) ◽  
pp. 17-27
Author(s):  
A. Yu. Popova ◽  
E. B. Ezhlova ◽  
A. A. Melnikova ◽  
L. A. Lukicheva ◽  
N. I. Nikitina ◽  
...  
Keyword(s):  
Humoral Immunity ◽  
Elderly Population ◽  
Age Groups ◽  
The Elderly ◽  
Population Immunity ◽  
Murmansk Region ◽  
Structure Of Population ◽  
Transport Workers ◽  
Unified Method

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%.

scholarly journals Declining prevalence of antibody positivity to SARS-CoV-2: a community study of 365,000 adults

2020 ◽  
Author(s):  
Helen Ward ◽  
Graham Cooke ◽  
Christina Atchison ◽  
Matthew Whitaker ◽  
Joshua Elliott ◽  
...  
Keyword(s):  
Adult Population ◽  
Age Groups ◽  
Asymptomatic Infection ◽  
Cross Sectional ◽  
Neutralization Activity ◽  
Population Immunity ◽  
Test Characteristics ◽  
Antibody Positivity ◽  
History Of ◽  
Second Wave

AbstractBackgroundThe prevalence and persistence of antibodies following a peak SARS-CoV-2 infection provides insights into its spread in the community, the likelihood of reinfection and potential for some level of population immunity.MethodsPrevalence of antibody positivity in England, UK (REACT2) with three cross-sectional surveys between late June and September 2020. 365104 adults used a self-administered lateral flow immunoassay (LFIA) test for IgG. A laboratory comparison of LFIA results to neutralization activity in panel of sera was performed.ResultsThere were 17,576 positive tests over the three rounds. Antibody prevalence, adjusted for test characteristics and weighted to the adult population of England, declined from 6.0% [5.8, 6.1], to 4.8% [4.7, 5.0] and 4.4% [4.3, 4.5], a fall of 26.5% [-29.0, −23.8] over the three months of the study. There was a decline between rounds 1 and 3 in all age groups, with the highest prevalence of a positive result and smallest overall decline in positivity in the youngest age group (18-24 years: −14.9% [-21.6, −8.1]), and lowest prevalence and largest decline in the oldest group (75+ years: −39.0% [-50.8, −27.2]); there was no change in antibody positivity between rounds 1 and 3 in healthcare workers (+3.45% [-5.7, +12.7]).The decline from rounds 1 to 3 was largest in those who did not report a history of COVID-19, (−64.0% [-75.6, −52.3]), compared to −22.3% ([-27.0, −17.7]) in those with SARS-CoV-2 infection confirmed on PCR.DiscussionThese findings provide evidence of variable waning in antibody positivity over time such that, at the start of the second wave of infection in England, only 4.4% of adults had detectable IgG antibodies using an LFIA. Antibody positivity was greater in those who reported a positive PCR and lower in older people and those with asymptomatic infection. These data suggest the possibility of decreasing population immunity and increasing risk of reinfection as detectable antibodies decline in the population.

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