Dynamics of the development of the epidemic of coronavirus infection and assessment of population immunity to SARS-COV-2 in the territory of the Kyrgyz Republic

Abstract

Objective: The aim of this study was to assess the dynamics of the development of the coronavirus infection epidemic and their relationship with the formation of population immunity to the SARS-CoV-2 virus among the population of the Kyrgyz Republic. Methods: The seroepidemiological study is population-based, prospective, cross-sectional, stratified by five age categories and was conducted in all nine geographical regions of the Kyrgyz Republic. Primary health care (PHC) organizations were selected by random sampling method and a list of people from each PHC was used to randomly select participants. All respondents were included in the study based on their prior informed consent. Participants were interviewed about age, gender, present symptoms of disease, seeking health care and hospitalization. The study materials were sera and questionnaire data of those who consented to the study. Results: Seroprevalence among population of the Kyrgyz Republic as a whole was in the first round -30.8% and in the second round -71.2%. The study of the seroprevalence rate by age showed that the lowest rates were found among children younger than 9 years: during the first round - (16.5 (1.4)%), in the second round - (51.4 (1.9)%). There was also an increase in the proportion of seropositive individuals in all regions. By region, seroprevalence in the first round ranged from 13.0% (9.7-16.3) to 62.7% (59.2-69.2), in the second round from 63.9 to 77.8%. In the first round of the study 925/1446 (64.0%) (95% CI 61.5-66.5) seropositive individuals had symptoms of COVID-19, and in the second round 1696/3372 or 50.3% (48.6-52.0), respectively. According to the results of all study rounds, the proportion of seeking medical care among the seropositive increases in parallel with the increasing age, so in the first round it ranged from 10.0 to 27.5% and in the second round from 6.2 to 37.5%. Conclusion: With the increasing prevalence of coronavirus infection, seroprevalence to SARS-CoV-2 virus increased in parallel, so that from July 2020 to February 2021 it increased by 2.3-fold, from 30.8% to 71.2%. By February 2021, 28.8% of the population remained susceptible to coronavirus infection. Among children aged 0-9 years, only 23.8% had symptoms of coronavirus infection, while in adults over 65 years of age- 60.3% had symptoms, which is 2.5 times higher than in children. Due to increased awareness of the population on prevention of coronavirus infection in the second round of the study, the percentage of seeking medical care increased by 3.6% compared to the first round (25.4% vs. 21.8%). Also, with the increasing possibility of hospitalization in the healthcare system of Kyrgyz Republic, the proportion of hospitalized patients increased by 4.6% (10.1% vs. 5.5%).

Keywords

• coronavirus infection
• sars-cov-2
• seroepidemiological study
• morbidity
• population immunity
• seropositivity