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. 

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 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.

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.

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 Manifestations of the Epidemic Process of Measles and Rubella at the Present Stage

2018 ◽  
Vol 17 (5) ◽  
pp. 45-53 ◽  
Author(s):  
A. A. Pozdnyakov ◽  
O. P. Chernyavskaya
Keyword(s):  
Statistical Significance ◽  
Age Groups ◽  
Present Stage ◽  
Microsoft Excel ◽  
Epidemic Process ◽  
Contact Number ◽  
Population Immunity ◽  
Younger Age ◽  
Rate Of Decline ◽  
Short Time

Relevance.Measles and rubella have been known to humanity for centuries. These two infections have a number of similarities. However, despite all the similarities and a single elimination program, it is not possible to achieve the same results by the level of the incidence of these infections. Goal. Identify common features and differences in the manifestations of the epidemic process of measles and rubella at the present stage and formulate a hypothesis on their explanation.Materials and methods. Methods of retrospective epidemiological analysis of morbidity were used: Evaluation of the statistical significance of the differences in indicators with the Student’s test. To compare the rate of decrease in the incidence of measles and rubella their exponential approximations using the method of least squares were used. To process the research data, the Microsoft Excel program was used.Results.In the pre-vaccination period, the incidence of measles was 4.6 times higher than rubella. For major infections in this period characterized by a pronounced cyclic morbidity, while the intervals between cyclical rises for measles are shorter, and the amplitude of cycles is higher. As the population was vaccinated, the incidence of these infections decreased, while the rate of decline in the incidence of rubella was higher than that of measles. Also, a faster decrease in morbidity and smoothing of the cyclicity, a transition to older age groups, a gradual exit from the incidence of younger age groups confirm that the rubella has a contact number less then measles.Conclusion.The current level of population immunity is sufficient to eliminate rubella in a relatively short time. For measles, which has greater contagiousness and a contact number, and is more demanding for population immunity, this level is not enough. As a consequence, rubella shows better «manageability» in immunization than measles.

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 The impact of protein-conjugate polysaccharide vaccines: an endgame for meningitis?

2013 ◽  
Vol 368 (1623) ◽  
pp. 20120147 ◽  
Author(s):  
Martin C. J. Maiden
Keyword(s):  
Herd Immunity ◽  
Age Groups ◽  
Population Level ◽  
Bacterial Diseases ◽  
Beneficial Effects ◽  
Health Innovations ◽  
Childhood Morbidity ◽  
Encapsulated Bacteria ◽  
Effective Public Health ◽  
The Impact

The development and implementation of conjugate polysaccharide vaccines against invasive bacterial diseases, specifically those caused by the encapsulated bacteria Neisseria meningitidis , Haemophilus influenzae and Streptococcus pneumoniae , has been one of the most effective public health innovations of the last 25 years. These vaccines have resulted in significant reductions in childhood morbidity and mortality worldwide, with their effectiveness due in large part to their ability to induce long-lasting immunity in a range of age groups. At the population level this immunity reduces carriage and interrupts transmission resulting in herd immunity; however, these beneficial effects can be counterbalanced by the selection pressures that immunity against carriage can impose, potentially promoting the emergence and spread of virulent vaccine escape variants. Studies following the implementation of meningococcal serogroup C vaccines improved our understanding of these effects in relation to the biology of accidental pathogens such as the meningococcus. This understanding has enabled the refinement of the implementation of conjugate polysaccharide vaccines against meningitis-associated bacteria, and will be crucial in maintaining and improving vaccine control of these infections. To date there is little evidence for the spread of virulent vaccine escape variants of the meningococcus and H. influenzae , although this has been reported in pneumococci.

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 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. 

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