Journal of microbiology, epidemiology and immunobiologyJournal of microbiology, epidemiology and immunobiology0372-93112686-7613Central Research Institute for Epidemiology94010.36233/0372-9311-2020-97-6-2UnknownDistribution of SARS-CоV-2 seroprevalence among residents of the Republic of Tatarstan during the COVID-19 epidemic periodPopovaA. Yu.<p>Anna Yu. Popova — D. Sci. (Med.), Prof., Head</p><p>127994, Moscow</p>fake@neicon.ruEzhlovaE. B.<p>Elena B. Ezhlova — Cand. Sci. (Med.), Deputy Head</p><p>127994, Moscow</p>fake@neicon.ruMelnikovaA. A.<p>Albina A. Melnikova — Cand. Sci. (Med.), Deputy Head Epidemiological surveillance department</p><p>127994, Moscow</p>fake@neicon.ruhttps://orcid.org/0000-0002-5651-1331PatyashinaM. A.<p>Marina A. Patyashina — Head</p><p>420011, Kazan</p>fake@neicon.ruhttps://orcid.org/0000-0002-6302-3993SizovaE. P.<p>Elena P. Sizova — chief physician</p><p>420061, Kazan</p>fake@neicon.ruYuzlibaevaL. R.<p>Lilia R. Yuzlibaeva — Head, Epidemic surveillance department</p><p>420011, Kazan</p>fake@neicon.ruhttps://orcid.org/0000-0002-8082-0302LyalinaL. V.<p>Lyudmila V. Lyalina — D. Sci. (Med.), Prof., Head, Laboratory of epidemiology of infectious and non-infectious diseases</p><p>197101, Saint Petersburg</p>fake@neicon.ruhttps://orcid.org/0000-0001-9921-3505SmirnovV. S.<p>Vyacheslav S. Smirnov — D. Sci. (Med.), Prof., leading researcher</p><p>197101, Saint Petersburg</p>vssmi@mail.ruhttps://orcid.org/0000-0002-2723-1496BadamshinaG. G.<p>Gulnara G. Badamshina — Head, Department of microbiological research</p><p>420061, Kazan</p>fake@neicon.ruhttps://orcid.org/0000-0003-0088-6422GoncharovaA. V.<p>Anna V. Goncharova — Head, Laboratory for especially dangerous and viral infections</p><p>420061, Kazan</p>fake@neicon.ruArbuzovaT. V.<p>Tatiana V. Arbuzova — junior researcher, Epidemiological monitoring and forecasting group</p><p>197101, Saint Petersburg</p>fake@neicon.ruhttps://orcid.org/0000-0002-3074-8656LomonosovaV. I.<p>Valeria I. Lomonosova — research assistant, Laboratory of epidemiology of infectious and non-infectious diseases</p><p>197101, Saint Petersburg</p>fake@neicon.ruhttps://orcid.org/0000-0002-4531-2724TotolianA. A.<p>Areg A. Totolian — D. Sci. (Med.), Prof., Academician of RAS, Director</p><p>197101, Saint Petersburg</p>pasteur@pasteurorg.ruhttps://orcid.org/0000-0003-4571-8799Federal Service for Surveillance on Consumer Rights Protection and Human WellbeingDepartment of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing for Tatarstan RepublicCenter for Hygiene and Epidemiology in Tatarstan RepublicSaint Petersburg Pasteur Institute200120219765185282001202120012021Copyright © 2021, Popova A.Y., Ezhlova E.B., Melnikova A.A., Patyashina M.A., Sizova E.P., Yuzlibaeva L.R., Lyalina L.V., Smirnov V.S., Badamshina G.G., Goncharova A.V., Arbuzova T.V., Lomonosova V.I., Totolian A.A.2021<p>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).</p>
<p><strong>The purpose</strong> 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.</p>
<p><strong>Materials and methods</strong>. 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.</p>
<p><strong>Results</strong>. 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 713 years (42.0%), children 1417 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%</p>
<p><strong>Conclusion</strong>. 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.</p>coronavirusesCOVID-19seroprevalenceRepublic of TatarstanpopulationкоронавирусыCOVID-19серопревалентностьРеспублика Татарстаннаселение[Faust J.S., del Rio C. Assessment of Deaths from COVID-19 and from Seasonal Influenza. JAMA Intern. Med. 2020; 180(8): 1045–6. https://doi.org/10.1001/jamainternmed.2020.2306][Nicomedes C.J.C., Avila R.M.A. An analysis on the panic during COVID-19 pandemic through an online form. J. Affect. Disord. 2020; 276: 14–22. https://doi.org/10.1016/j.jad.2020.06.046][Lenzen M., Li M., Malik A., Pomponi F., Sun Y.Y., Wiedmann T., et al. Global socio-economic losses and environmental gains from the Coronavirus pandemic. PLoS One. 2020; 15(7): e0235654. https://doi.org/10.1371/journal.pone.0235654][Randolph H.E., Barreiro L.B. Herd immunity: understanding COVID-19. Immunity. 2020; 52(5): 737–41. https://doi.org/10.1016/j.immuni.2020.04.012][Gomes M.G.M., Corder R.M., King J.G., Langwig K.E., Souto-Maior C., Carneiro J., et al. Individual variation in susceptibility or exposure to SARS-CoV-2 lowers the herd immunity threshold. medRxiv. Preprint. https://doi.org/10.1101/2020.04.27.20081893][Robison D., Lhermie G. Living with COVID-19: A systemic and multi-criteria approach to enact evidence-based health policy. Front. Public Health. 2020; 8: 294.][Попова А.Ю., Ежлова Е.Б., Мельникова А.А., Башкетова Н.С., Фридман Р.К., Лялина Л.В. и др. Популяционный иммунитет к вирусу SARS-CoV-2 среди населения Санкт-Петербурга в активную фазу эпидемии COVID-19. Проблемы особо опасных инфекций. 2020; 3: 124–130. DOI: 10.21055/0370-1069-2020-3-124-130][Newcombe R.G. Two-sided confidence intervals for the single proportion: comparison of seven methods. Stat. Med. 1998; 17(8): 857–87. https://doi.org/10.1002/(sici)10970258(19980430)17:8%3C857::aid-sim777%3E3.0.co;2-e][Ng K., Faulkner N., Cornish G., Rosa A., Earl C., Wrobel A., et al. Preexisting and de novo humoral immunity to SARS-CoV-2 in humans. Science. 2020; eabe1107. https://doi.org/10.1126/science.abe1107][Walsh K.A., Jordan K., Clyne B., Rohde D., Drummond L., Byrne P., et al. SARS-CoV-2 detection, viral load and infectivity over the course of an infection. J. Infect. 2020; 81(3): 357–71. https://doi.org/10.1016/j.jinf.2020.06.067][Okba N.M.A., Müller M.A., Li W., Wang C., Kessel C.H.G., Corman V.M., et al. Severe acute respiratory syndrome coronavirus 2 — specific antibody responses in coronavirus disease patients. Emerg. Infect. Dis. 2020; 26(7): 1478–88. https://doi.org/10.3201/eid2607.200841][Попова А.Ю., Ежлова Е.Б., Мельникова А.А., Историк О.А., Мосевич О.С., Лялина Л.В. и др. Опыт оценки популяционного иммунитета к SARS-CоV-2 среди населения Ленинградской области в период эпидемии COVID-19. Проблемы особо опасных инфекций. 2020; 3:114–123. DOI: 10.21055/0370-1069-2020-3-114-123.][Cai J., Sun W., Huang J., Gamber M., Wu J., He G. Indirect virus transmission in cluster of COVID-19 cases, Wenzhou, China, 2020. Emerg. Infect. Dis. 2020; 26(6): 1343–5. https://doi.org/10.3201/eid2606.200412][Смирнов В.С., Зарубаев В.В., Петленко С.В. Биология возбудителей и контроль гриппа и ОРВИ. СПб.: Гиппократ; 2020.][Huang A.T., Garcia-Carreras B., Hitchings M.D., Yang B., Katzelnick L.C., Rattigan S.M., et al. A systematic review of antibody mediated immunity to coronaviruses: antibody kinetics, correlates of protection, and association with severity. Nat. Commun. 2020; 11(1): 4704. https://doi.org/10.1038/s41467-020-18450-4]