Peculiarities of Seroprovalence to SARS-CoV-2 in the Population of the Middle and Southern Urals in the Early Period of the COVID-19 Pandemic

Abstract

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.

Longitudinal Randomized Cohort Study of SARS-CoV-2 Antibody Seroprevalence in the St. Petersburg Population

“…From a practical point of view, epidemiological analysis of the state of collective immunity using serological methods (for determining the prevalence of SARS-CoV-2 Abs) and other epidemiological analysis approaches are more appropriate [ 12 , 13 ]. This article continues our previous publications analyzing SARS-CoV-2 Ab seroprevalence, such as our cross-sectional study of herd immunity in the St. Petersburg population [ 14 ] conducted in the early period of COVID-19 incidence (13–20 June 2020), as well as longitudinal seromonitoring of the population in 26 regions of Russia [ 15 , 16 , 17 , 18 , 19 , 20 ]. Features of seroprevalence in Belarus and Kyrgyzstan (2020–21) were also analyzed [ 21 , 22 ].…”

“…The latter was mainly reduced to the relief of certain symptoms of acute infection [ 53 , 54 , 55 ]. In this regard, the humoral response remained the main method of control as a tool for regulating the infectious process [ 3 , 4 , 5 , 6 , 15 , 16 , 17 ]. Monitoring of SARS-CoV-2 seropositivity among the population in the first stages showed two unidirectional processes: simultaneous increases in the levels of Abs (to both Nc and RBD) in both children and adults ( Figure 2 ).…”

Longitudinal Randomized Cohort Study of SARS-CoV-2 Antibody Seroprevalence in the St. Petersburg Population

“…From a practical point of view, epidemiological analysis of the state of collective immunity using serological methods (for determining the prevalence of SARS-CoV-2 Abs) and other epidemiological analysis approaches are more appropriate [12,13]. This article continues our previous publications analyzing SARS-CoV-2 Ab seroprevalence, such as our cross-sectional study of herd immunity in the St. Petersburg population [14] conducted in the early period of COVID-19 incidence (13-20/06/2020), as well as longitudinal seromonitoring of the population in 26 regions of Russia [15][16][17][18][19][20]. Features of seroprevalence in Belarus and Kyrgyzstan (2020-21) were also analyzed [21,22].…”

“…The latter was mainly reduced to relief of certain symptoms of acute infection [53,54,55]. In this regard, the humoral response remained the main method of control as a tool for regulating the infectious process [3,4,5,6,15,16,17]. Monitoring of SARS-CoV-2 seropositivity among the population in the first stages showed two unidirectional processes: simultaneous increases in the levels of Abs (to both Nc and RBD) in both children and adults (Fig.…”