{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T18:50:52Z","timestamp":1768416652147,"version":"3.49.0"},"reference-count":70,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2021,8,19]],"date-time":"2021-08-19T00:00:00Z","timestamp":1629331200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>The SARS-CoV-2 pandemic, which came to Russia in March 2020, is accompanied by morbidity level changes and can be tracked using serological monitoring of a representative population sample from Federal Districts (FDs) and individual regions. In a longitudinal cohort study conducted in 26 model regions of Russia, distributed across all FDs, we investigated the distribution and cumulative proportions of individuals with antibodies (Abs) to the SARS-CoV-2 nucleocapsid antigen (Ag), in the period from June to December 2020, using a three-phase monitoring process. In addition, during the formation of the cohort of volunteers, the number of seropositive convalescents, persons who had contact with patients or COVID-19 convalescents, and the prevalence of asymptomatic forms of infection among seropositive volunteers were determined. According to a uniform methodology, 3 mL of blood was taken from the examined individuals, and plasma was separated, from which the presence of Abs to nucleocapsid Ag was determined on a Thermo Scientific Multiascan FC device using the \u201cELISA anti-SARS-CoV-2 IgG\u201d reagent set (prod. Scientific Center for Applied Microbiology and Biotechnology), in accordance with the developer\u2019s instructions. Volunteers (74,158) were surveyed and divided into seven age groups (1\u201317, 18\u201329, 30\u201339, 40\u201349, 59\u201359, 60\u201369, and 70+ years old), among whom 14,275 were identified as having antibodies to SARS-CoV-2. The average percent seropositive in Russia was 17.8% (IQR: 8.8\u201323.2). The largest proportion was found among children under 17 years old (21.6% (IQR: 13.1\u201331.7). In the remaining groups, seroprevalence ranged from 15.6% (IQR: 8\u201321.1) to 18.0% (IQR: 13.4\u201322.6). During monitoring, three (immune) response groups were found: (A) groups with a continuous increase in the proportion of seropositive; (B) those with a slow rate of increase in seroprevalence; and (C) those with a two-phase curve, wherein the initial increase was replaced by a decrease in the percentage of seropositive individuals. A significant correlation was revealed between the number of COVID-19 convalescents and contact persons, and between the number of contacts and healthy seropositive volunteers. Among the seropositive volunteers, more than 93.6% (IQR: 87.1\u201394.9) were asymptomatic. The results show that the COVID-19 pandemic is accompanied by an increase in seroprevalence, which may be important for the formation of herd immunity.<\/jats:p>","DOI":"10.3390\/v13081648","type":"journal-article","created":{"date-parts":[[2021,8,19]],"date-time":"2021-08-19T09:58:06Z","timestamp":1629367086000},"page":"1648","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":29,"title":["SARS-CoV-2 Seroprevalence Structure of the Russian Population during the COVID-19 Pandemic"],"prefix":"10.3390","volume":"13","author":[{"given":"Anna Y.","family":"Popova","sequence":"first","affiliation":[{"name":"Federal Service for Supervision of Consumer Rights Protection and Human Welfare, 127994 Moscow, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2723-1496","authenticated-orcid":false,"given":"Viacheslav S.","family":"Smirnov","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elena E.","family":"Andreeva","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in Moscow, 129626 Moscow, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elena A.","family":"Babura","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Kaliningrad Region, 236040 Kaliningrad, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sergey V.","family":"Balakhonov","sequence":"additional","affiliation":[{"name":"Irkutsk Research Anti-Plague Institute, 664047 Irkutsk, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Natalia S.","family":"Bashketova","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in St. Petersburg, 191025 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Svetlana A.","family":"Bugorkova","sequence":"additional","affiliation":[{"name":"Russian Research Anti-Plague Institute \u201cMicrobe\u201d, 410005 Saratov, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maxim V.","family":"Bulanov","sequence":"additional","affiliation":[{"name":"Center for Hygiene and Epidemiology of the Vladimir Region, 600005 Vladimir, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Natalia. N.","family":"Valeullina","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Chelyabinsk Region, 454091 Chelyabinsk, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Viacheslav. V.","family":"Vetrov","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dmitriy. V.","family":"Goryaev","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Krasnoyarsk Territory, 660049 Krasnoyarsk, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tatyana N.","family":"Detkovskaya","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Primorsky Krai, 690950 Vladivostok, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elena B.","family":"Ezhlova","sequence":"additional","affiliation":[{"name":"Federal Service for Supervision of Consumer Rights Protection and Human Welfare, 127994 Moscow, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Natalia N.","family":"Zaitseva","sequence":"additional","affiliation":[{"name":"Nizhny Novgorod I. N. Blokhina Research Institute of Epidemiology and Microbiology, 603950 Nizhny Novgorod, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Olga A.","family":"Istorik","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Leningrad Region, 192029 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Irina. V.","family":"Kovalchuk","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Stavropol Territory, 355008 Stavropol, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dmitriy N.","family":"Kozlovskikh","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Sverdlovsk Region, 620078 Yekaterinburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Svetlana Y.","family":"Kombarova","sequence":"additional","affiliation":[{"name":"G. N. Gabrichevsky Moscow Research Institute for Epidemiology and Microbiology, 125212 Moscow, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Olga. P.","family":"Kurganova","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Amur Region, 675002 Blagoveshchensk, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alexander. E.","family":"Lomovtsev","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Tula Region, 300045 Tula, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lena A.","family":"Lukicheva","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Murmansk Region, 183038 Murmansk, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ludmila V.","family":"Lyalina","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Albina. A.","family":"Melnikova","sequence":"additional","affiliation":[{"name":"Federal Service for Supervision of Consumer Rights Protection and Human Welfare, 127994 Moscow, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Olga M.","family":"Mikailova","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Moscow Region, 141014 Mytishchi, Moscow Region, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alexei K.","family":"Noskov","sequence":"additional","affiliation":[{"name":"Rostov-on-Don Research Anti-Plague Institute, 344000 Rostov-on-Don, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ludmila N.","family":"Noskova","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration for the Astrakhan Region, 414057 Astrakhan, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elena E.","family":"Oglezneva","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Belgorod Region, 308023 Belgorod, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tatyana P.","family":"Osmolovskaya","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Krasnodar Territory, 350000 Krasnodar, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marina A.","family":"Patyashina","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Republic of Tatarstan, 420111 Kazan, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Natalia A.","family":"Penkovskaya","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Republic of Crimea, 295034 Simferopol, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lada V.","family":"Samoilova","sequence":"additional","affiliation":[{"name":"Rospotrebnadzor Administration in the Novosibirsk Region, 630132 Novosibirsk, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tatyana F.","family":"Stepanova","sequence":"additional","affiliation":[{"name":"Tyumen Research Institute of Regional Infectious Pathology, 625026 Tyumen, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Olga E.","family":"Trotsenko","sequence":"additional","affiliation":[{"name":"Khabarovsk Research Institute of Epidemiology and Microbiology, 680000 Khabarovsk, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Areg A.","family":"Totolian","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,19]]},"reference":[{"key":"ref_1","unstructured":"Smirnov, V.S., Zarubaev, V.V., and Petlenko, S.V. 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