Clinical Manifestations of COVID-19 in Different Periods of the Pandemic in Persons from Occupational Risk Groups of Infection

Abstract

Relevance. One of the most affected by the new coronavirus infection (COVID-19) groups of the population were medical workers who have high risks of infection in the performance of professional dutiesAim. Analysis the clinical manifestations of COVID–19 in different periods of the pandemic in medical organizations, taking into account the genetic variability of circulating strains of SARSCoV- 2 and vaccination status.Materials and methods. To study the clinical manifestations of coronavirus infection, an online survey of medical workers in a large industrial region was conducted in March 2022 using a specially designed anonymous questionnaire. The total number of respondents was 3,078. Clinical manifestations were analyzed during five epidemic rises in the incidence of COVID-19 from March 2020 to March 2022. To assess the SARS-CoV-2 virus strains circulating in the region, data from the GISAID database (the first and second waves of the pandemic, n = 298) and the results of PCR studies in the laboratory of UMMC-Health LLC (third - fifth waves, n = 349) were used.Results and discussion. In the first and second epidemic rises of morbidity associated with SARS-CoV-2 strains B.1. and B.1.1, the structure of clinical forms did not significantly differ: 3.6% and 3.9% were asymptomatic forms, 61.3% – variants of acute respiratory infection (AR I) and 35.1% and 34.8% - pneumonia, accordingly. In the third epidemic upsurge caused by the Delta variant (V.1.617.2), the structure of clinical forms did not undergo significant changes. In the fourth epidemic rise in morbidity, also associated with the spread of the Delta variant, the share of ARI in the structure of clinical forms increased to 77.0%, and pneumonia decreased to 21.3%.In the fifth wave of the pandemic caused by the Omicron gene variant (B.1.1.529), there was an increase to 91.3% of the proportion of mild clinical forms and a decrease to 7.1% of forms with lung damage. The frequency of detection of general infectious symptoms, upper respiratory tract lesions and neurological manifestations of COVID-19 had statistically significant differences in different periods of the pandemic. Whereas the frequency of gastrointestinal disorders did not significantly differ. The high clinical efficacy of vaccination has been shown – in ter ms of a 3.6-fold reduction in the chances of developing moderate and severe forms of the disease.Conclusion. Based on the results of the study, new data were obtained on the features of the clinical manifestations of COVID-19 in different periods of the pandemic with the change of genetic variants of the pathogen and the role of vaccination in preventing the development of moderate and severe clinical forms of infection was shown.