{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T04:31:11Z","timestamp":1772253071641,"version":"3.50.1"},"reference-count":56,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2022,4,27]],"date-time":"2022-04-27T00:00:00Z","timestamp":1651017600000},"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>Introduction. Since the detection of the first COVID-19 patient, 2 years have passed, during which more than 287,862,000 people have fallen ill globally, of which about 1.9% died. The implementation of SARS-CoV-2 control programs required efforts from almost all countries. An important direction in the fight against COVID-19 has been the formation of herd immunity, the main tool for managing the pandemic. Study goal. The aim of the study was to assess the seroprevalence of antibodies (Abs) to SARS-CoV-2 nucleocapsid (Nc) and receptor binding domain (RBD) in the St. Petersburg population during the COVID-19 pandemic. Materials and methods. A longitudinal cohort randomized monitoring study of Ab seroprevalence (SARS-CoV-2 Nc, RBD) was organized and conducted according to a unified methodology developed by Rospotrebnadzor with the participation of the St. Petersburg Pasteur Institute. For this purpose, a cohort was formed of 1000 volunteers who participated in all five stages of seromonitoring. The cohort was divided into seven age groups: 1\u201317; 18\u201329; 30\u201339; 40\u201349; 50\u201359; 60\u201369; 70; and older (70+) years. Seropositivity levels (Nc, RBD) were assessed by quantitative and qualitative enzyme immunoassays. During the second year of monitoring, some volunteers were vaccinated with the GamCOVIDVac (84%) or EpiVacCorona (11.6%) vaccines approved in Russia. Statistical processing was carried out using Excel 2010. Confidence intervals for shares and percentages (95% CI) were calculated using the method of A. Wald and J. Wolfowitz with adjustment (A. Agresti, B.A. Coull). The statistical significance of differences was calculated by z-test, using the appropriate online calculator (p &lt; 0.05) unless indicated. Results. There was a trend toward an increase in Nc seropositivity in stages 1\u20133 of seromonitoring, with a decrease in stages 4\u20135 among children and adults. The share of RBD seropositive steadily increased during all five stages of seromonitoring. The most frequent finding was low anti-RBD Abs levels (22.6\u2013220 BAU\/mL). High Ab levels were recorded statistically significantly less frequently. Asymptomatic forms were observed in 84\u201388% of SARS-CoV-2 seropositive volunteers. By the fifth stage of monitoring, this indicator significantly decreased to 69.8% (95% CI: 66.1\u201373.4). The monitoring revealed a statistically significant increase in anti-RBD Abs alongside a statistically significant decrease in the proportion of Nc seropositives. This dynamic was especially characteristic of persons vaccinated with GamCOVIDVac. Conclusion. Prior to the use of specific vaccines, a seroprevalence of anti-Nc Abs was noted. After the introduction of the GamCOVIDVac vaccine in adults, a decrease in the level of anti-Nc Abs was noted due to an increase in the proportion of RBD seropositive persons.<\/jats:p>","DOI":"10.3390\/v14050913","type":"journal-article","created":{"date-parts":[[2022,4,27]],"date-time":"2022-04-27T22:20:20Z","timestamp":1651098020000},"page":"913","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Longitudinal Randomized Cohort Study of SARS-CoV-2 Antibody Seroprevalence in the St. Petersburg Population"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2723-1496","authenticated-orcid":false,"given":"Vyacheslav S.","family":"Smirnov","sequence":"first","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Liudmila V.","family":"Lyalina","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anzhelika M.","family":"Milichkina","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Irina V.","family":"Khamitova","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elena V.","family":"Zueva","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Valery A.","family":"Ivanov","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1805-7817","authenticated-orcid":false,"given":"Vitaly S.","family":"Zaguzov","sequence":"additional","affiliation":[{"name":"Saint Petersburg Pasteur Institute, 197101 St. Petersburg, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4571-8799","authenticated-orcid":false,"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":[[2022,4,27]]},"reference":[{"key":"ref_1","unstructured":"(2021, November 03). Coronavirus-Monitor. Available online: https:\/\/coronavirus-monitor.info\/."},{"key":"ref_2","unstructured":"(2002, December 16). Available online: https:\/\/www.gov.spb.ru\/press\/governor\/225782\/."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"22970","DOI":"10.1038\/s41598-021-00083-2","article-title":"The herd-immunity threshold must be updated for multi-vaccine strategies and multiple variants","volume":"11","author":"Yadegari","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"547314","DOI":"10.3389\/fcell.2020.547314","article-title":"How to Understand \u201cHerd Immunity\u201d in COVID-19 Pandemic","volume":"8","author":"Xia","year":"2020","journal-title":"Front. Cell Dev. Biol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1038\/s41577-020-00451-5","article-title":"COVID-19 herd immunity: Where are we?","volume":"20","author":"Fontanet","year":"2020","journal-title":"Nat. Rev. Immunol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"737","DOI":"10.1016\/j.immuni.2020.04.012","article-title":"Herd Immunity: Understanding COVID-19","volume":"52","author":"Randolph","year":"2020","journal-title":"Immunity"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"taaa021","DOI":"10.1093\/jtm\/taaa021","article-title":"The reproductive number of COVID-19 is higher compared to SARS coronavirus","volume":"27","author":"Liu","year":"2020","journal-title":"J. Travel. Med."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Jin, Y., Yang, H., Ji, W., Wu, W., Chen, S., Zhang, W., and Duan, G. (2020). Virology, Epidemiology, Pathogenesis, and Control of COVID-19. Viruses, 12.","DOI":"10.3390\/v12040372"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1470","DOI":"10.3201\/eid2607.200282","article-title":"High Contagiousness and Rapid Spread of Severe Acute Respiratory Syndrome Coronavirus 2","volume":"26","author":"Sanche","year":"2020","journal-title":"Emerg. Infect. Dis."},{"key":"ref_10","first-page":"CD006207","article-title":"Physical interventions to interrupt or reduce the spread of respiratory viruses","volume":"2020","author":"Jefferson","year":"2020","journal-title":"Cochrane Database Syst. Rev."},{"key":"ref_11","first-page":"5011","article-title":"Coronavirus herd immunity optimizer (CHIO)","volume":"33","author":"Alyasseri","year":"2020","journal-title":"Neural Comput. Appl."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1111\/joim.13372","article-title":"Immunity to SARS-CoV-2 induced by infection or vaccination","volume":"291","author":"Dopico","year":"2021","journal-title":"J. Intern. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"835","DOI":"10.1186\/s12879-021-06550-5","article-title":"Prevalence and associated characteristics of anti-SARS-CoV-2 antibodies in Mexico 5 months after pandemic arrival","volume":"21","year":"2021","journal-title":"BMC Infect. Dis."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"124","DOI":"10.21055\/0370-1069-2020-3-124-130","article-title":"Herd Immunity to SARS-CoV-2 among the Population in Saint-Petersburg during the COVID-19 Epidemic","volume":"3","author":"Popova","year":"2020","journal-title":"Probl. Osob. Opasnykh Infektsii = Probl. Part. Danger. Infect."},{"key":"ref_15","first-page":"297","article-title":"Features of developing SARS-CoV-2 nucleocapsid protein population-based seroprevalence during the first wave of the COVID-19 epidemic in the Russian Federation","volume":"11","author":"Popova","year":"2021","journal-title":"Russ. J. Infect. Immun. = Infektsiya Immun."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Popova, A.Y., Smirnov, V.S., Andreeva, E.E., Babura, E.A., Balakhonov, S.V., Bashketova, N.S., Bugorkova, S.A., Bulanov, M.V., Valeullina, N.N., and Vetrov, V.V. (2021). SARS-CoV-2 seroprevalence structure of the russian population during the COVID-19 pandemic. Viruses, 13.","DOI":"10.3390\/v13081648"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"8","DOI":"10.31631\/2073-3046-2021-20-3-8-18","article-title":"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","volume":"20","author":"Popova","year":"2021","journal-title":"Epidemiol. Vaccinal Prev."},{"key":"ref_18","first-page":"253","article-title":"Herd immunity to SARS-CoV-2 in the population of the Southern regions of the Far East of Russia","volume":"6","author":"Popova","year":"2021","journal-title":"Acta Biomed. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"97","DOI":"10.24110\/0031-403X-2021-100-3-97-106","article-title":"Peculiarities of SARS-CoV-2 nucleocapsid in children during the COVID-19 epidemic of 2020","volume":"100","author":"Popova","year":"2021","journal-title":"Pediatriya Named After GN Speransky"},{"key":"ref_20","first-page":"228","article-title":"Structure of herd immunity to SARS-CoV-2 in the Krasnoyarsk region population in the COVID-19 epidemic","volume":"6","author":"Popova","year":"2021","journal-title":"Acta Biomed. Sci."},{"key":"ref_21","first-page":"887","article-title":"Herd immunity to SARS-CoV-2 among the population of the Republic of Belarus amid the COVID-19 pandemic","volume":"11","author":"Popova","year":"2021","journal-title":"Russ. J. Infect. Immun. = Infektsiya Immun."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Popova, A.Y., Kasymov, O.T., Smolenski, V.Y., Smirnov, V.S., Egorova, S.A., Nurmatov, Z.S., Milichkina, A.M., Suranbaeva, G.S., Khamitova, I.V., and Zueva, E.V. (Res. Sq., 2021). SARS-CoV-2 Herd Immunity of the Kyrgyz Population in 2021, Res. Sq., preprint.","DOI":"10.21203\/rs.3.rs-1138128\/v1"},{"key":"ref_23","first-page":"609","article-title":"Methodology for assessing herd immunity to the SARS-CoV-2 virus in the context of the COVID-19 pandemic","volume":"11","author":"Popova","year":"2021","journal-title":"Russ. J. Infect. Immun. = Infektsiya Immun."},{"key":"ref_24","unstructured":"WHO (2021, August 18). Protocol for a Population-Based Age-Stratified Sero-Epidemiological Study of COVID-19 Infection in Humans. Version 2.0. 2020. Available online: https:\/\/apps.who.int\/iris\/bitstream\/handle\/10665\/332188\/WHO-2019CoV-Seroepidemiology-2020.2-rus.pdf."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"887","DOI":"10.1016\/S0140-6736(20)31866-3","article-title":"Safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine in two formulations: Two open, non-randomised phase 1\/2 studies from Russia","volume":"396","author":"Logunov","year":"2020","journal-title":"Lancet"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"642","DOI":"10.1016\/S0140-6736(21)00191-4","article-title":"Sputnik V COVID-19 vaccine candidate appears safe and effective","volume":"397","author":"Jonesa","year":"2021","journal-title":"Lancet"},{"key":"ref_27","first-page":"283","article-title":"A single blind, placebo-controlled randomized study of the safety, reactogenicity and immunogenicity of the \u201cEpiVacCorona\u201d Vaccine for the prevention of COVID-19, in volunteers aged 18\u201360 years (phase I\u2013II)","volume":"11","author":"Ryzhikov","year":"2021","journal-title":"Russ. J. Infect. Immun. = Infektsiya Immun."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1214\/aoms\/1177732209","article-title":"Confidence Limits for Continuous Distribution Functions","volume":"10","author":"Wald","year":"1939","journal-title":"Ann. Math. Stat."},{"key":"ref_29","first-page":"119","article-title":"Approximate Is Better than \u201cExact\u201d for Interval Estimation of Binomial Proportions","volume":"52","author":"Agresti","year":"1998","journal-title":"Am. Stat."},{"key":"ref_30","unstructured":"Significant Difference Calculator (z-Test) (2021, October 07). RADAR Research Company. (In Russian)."},{"key":"ref_31","first-page":"319","article-title":"Winter of Omicron\u2014The Evolving COVID-19 Pandemic","volume":"22","author":"Omer","year":"2021","journal-title":"JAMA"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"106716","DOI":"10.1016\/j.rmed.2021.106716","article-title":"Investigating the aggressiveness of the COVID-19 Omicron variant and suggestions for possible treatment options","volume":"191","author":"Mohiuddin","year":"2021","journal-title":"Respir. Med."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"n3079","DOI":"10.1136\/bmj.n3079","article-title":"COVID-19: Omicron and the need for boosters","volume":"375","author":"Mahase","year":"2021","journal-title":"BMJ"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Yang, H.S., Costa, V., Racine-Brzostek, S.E., Acker, K.P., Yee, J., Chen, Z., Karbaschi, M., Zuk, R., Rand, S., and Sukhu, A. (2021). Association of Age With SARS-CoV-2 Antibody Response. JAMA Netw. Open, 4.","DOI":"10.1001\/jamanetworkopen.2021.4302"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"793953","DOI":"10.3389\/fimmu.2021.793953","article-title":"Sequential Analysis of Binding and Neutralizing Antibody in COVID-19 Convalescent Patients at 14 Months After SARS-CoV-2 Infection","volume":"12","author":"Rosati","year":"2021","journal-title":"Front. Immunol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1038\/s41467-021-27649-y","article-title":"Dynamics of spike-and nucleocapsid specific immunity during long-term follow-up and vaccination of SARS-CoV-2 convalescents","volume":"13","author":"Koerber","year":"2022","journal-title":"Nat. Commun."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"722027","DOI":"10.3389\/fimmu.2021.722027","article-title":"Occurrence of COVID-19 Symptoms During SARS-CoV-2 Infection Defines Waning of Humoral Immunity","volume":"12","author":"Wu","year":"2021","journal-title":"Front. Immunol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1016\/S0140-6736(20)32651-9","article-title":"Infectivity of asymptomatic versus symptomatic COVID-19","volume":"397","author":"Sayampanathan","year":"2021","journal-title":"Lancet"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"656","DOI":"10.1016\/j.ijid.2021.02.100","article-title":"The high prevalence of asymptomatic SARS-CoV-2 infection reveals the silent spread of COVID-19","volume":"105","author":"Almadhi","year":"2021","journal-title":"Int. J. Infect. Dis."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.immuni.2020.12.009","article-title":"T Cell Memory: Understanding COVID-19","volume":"54","author":"Jarjour","year":"2021","journal-title":"Immunity"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.it.2020.11.002","article-title":"T Cells: Warriors of SARS-CoV-2 Infection","volume":"42","author":"Prattichizzo","year":"2021","journal-title":"Trends Immunol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1076","DOI":"10.1016\/j.chom.2021.05.010","article-title":"SARS-CoV-2 human T cell epitopes: Adaptive immune response against COVID-19","volume":"29","author":"Grifoni","year":"2021","journal-title":"Cell Host Microbe"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"861","DOI":"10.1016\/j.cell.2021.01.007","article-title":"Adaptive immunity to SARS-CoV-2 and COVID-19","volume":"184","author":"Sette","year":"2021","journal-title":"Cell"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"101505","DOI":"10.1016\/j.smim.2021.101505","article-title":"T cell immunity to SARS-CoV-2","volume":"55","author":"Niessl","year":"2021","journal-title":"Semin. Immunol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1093\/infdis\/jiab256","article-title":"Persisting Salivary IgG Against SARS-CoV-2 at 9 Months After Mild COVID-19: A Complementary Approach to Population Surveys","volume":"224","author":"Alkharaan","year":"2021","journal-title":"J. Infect. Dis."},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Huynh, A., Arnold, D.M., Smith, J.W., Moore, J.C., Zhang, A., Chagla, Z., Harvey, B.J., Stacey, H.D., Ang, J.C., and Clare, R. (2021). Characteristics of Anti-SARS-CoV-2 Antibodies in Recovered COVID-19 Subjects. Viruses, 13.","DOI":"10.3390\/v13040697"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"2802","DOI":"10.1016\/j.sjbs.2021.02.011","article-title":"Durability of the humoral immune response in recovered COVID-19 patients","volume":"28","author":"Mahallawi","year":"2021","journal-title":"Saudi J. Biol. Sci."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"ofaa555","DOI":"10.1093\/ofid\/ofaa555","article-title":"CDC COVID-19 Response. ARS-CoV-2 Serologic Assay Needs for the Next Phase of the US COVID-19 Pandemic Response Open","volume":"8","author":"Gundlapalli","year":"2020","journal-title":"Forum Infect. Dis."},{"key":"ref_49","unstructured":"(2022, January 09). The Coronavirus in SPB, Available online: https:\/\/www.gov.spb.ru\/covid-19\/."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1821","DOI":"10.1002\/jmv.27541","article-title":"OMICRON (B.1.1.529): A new SARS-CoV-2 variant of concern mounting worldwide fear","volume":"94","author":"Thakur","year":"2021","journal-title":"J. Med. Virol."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"102779","DOI":"10.1016\/j.jaut.2021.102779","article-title":"Omicron SARS-CoV-2 variant: Unique features and their impact on pre-existing antibodies","volume":"126","author":"Kannan","year":"2022","journal-title":"J. Autoimmun."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"664","DOI":"10.1089\/vim.2021.0213","article-title":"Omicron: A Speculation on Its Potential Superpowers","volume":"34","author":"Russell","year":"2021","journal-title":"Viral Immunol."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1208\/s12248-020-00532-2","article-title":"Recent Developments on Therapeutic and Diagnostic Approaches for COVID-19","volume":"23","author":"Majumder","year":"2021","journal-title":"AAPS J."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1007\/s10238-020-00671-y","article-title":"Emerging treatment strategies for COVID-19 infection","volume":"21","author":"Gavriatopoulou","year":"2021","journal-title":"Clin. Exp. Med."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"446","DOI":"10.15789\/2220-7619-SPO-1470","article-title":"Some opportunities for immunotherapy in coronavirus infection","volume":"10","author":"Smirnov","year":"2020","journal-title":"Russ. J. Infect. Immun."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"762","DOI":"10.1038\/s41577-021-00631-x","article-title":"The immunology of asymptomatic SARS-CoV-2 infection: What are the key questions","volume":"21","author":"Boyton","year":"2021","journal-title":"Nat. Rev. Immunol."}],"container-title":["Viruses"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1999-4915\/14\/5\/913\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:02:07Z","timestamp":1760137327000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1999-4915\/14\/5\/913"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,4,27]]},"references-count":56,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2022,5]]}},"alternative-id":["v14050913"],"URL":"https:\/\/doi.org\/10.3390\/v14050913","relation":{"has-preprint":[{"id-type":"doi","id":"10.20944\/preprints202204.0165.v1","asserted-by":"object"}]},"ISSN":["1999-4915"],"issn-type":[{"value":"1999-4915","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,4,27]]}}}