Herd Immunity to SARS-CoV-2 among the Population in Saint-Petersburg during the COVID-19 Epidemic

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 an...

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Published in:	Problemy osobo opasnyh infekcij no. 3; pp. 124 - 130
Main Authors:	Popova, A. Yu, Ezhlova, E. B., Mel’nikova, A. A., Bashketova, N. S., Fridman, R. K., Lyalina, L. V., Smirnov, V. S., Chkhindzheriya, I. G., Grechaninova, T. A., Agapov, K. A., Arsent’eva, N. A., Bazhenova, N. A., Batsunov, O. K., Danilova, E. M., Zueva, E. V., Komkova, D. V., Kuznetsova, R. N., Lyubimova, N. E., Markova, A. N., Khamitova, I. V., Lomonosova, V. I., Vetrov, V. V., Milichkina, A. M., Dedkov, V. G., Totolyan, A. A.
Format:	Journal Article
Language:	English
Published:	Federal Government Health Institution, Russian Research Anti-Plague Institute “Microbe” 22-10-2020
Subjects:	asymptomatic infection coronavirus sars-cov-2 covid-19 incidence seroprevalence
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Summary:	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.
ISSN:	0370-1069 2658-719X
DOI:	10.21055/0370-1069-2020-3-124-130