NEW CORONAVIRUS INFECTION EPIDEMIC PECULIARITIES IN THE KHABAROVSK KRAI (PRELIMINARY RESULTS)

Epidemiological analysis based on Rospotrebnadzor situation reports, materials of Khabarovsk krai Rospotrebnadzor regional office and FBUZ “Center of hygiene and epidemiology in the Khabarovsk krai” concerning COVID-19 incidence in constituent entities of the Khabarovsk krai was performed. In order to identify certain stages of COVID-19 epidemic an average index of weekly incidence growth rate was utilized. In order to evaluate connection between investigated indices correlation and regression analysis were calculated. Four stages of epidemic development based on time-dependent growth rate of COVID-19 incidence was statistically determined in the Khabarovsk krai. First stage lasted from March 19 to April 12 and was mostly specified by isolated imported cases of COVID-19. Second stage lasted from April 13 to June 26, 2020 and was the longest period with most significant increase of incidence rates. Second stage was divided into 3 periods with different incidence growth rates. During the first period of the second stage (April 13 – May 24) strict measures were taken such as self-isolation and unprecedented restrictive policy measures and its features were as follows: cases of the disease in medical organizations and highest rates of asymptomatic COVID-19 cases were revealed. During the second period of the second stage of the epidemic (May 25-June 28) some of the restrictive measures were lifted and part of business enterprises resumed their work which lead to an increase of COVID-19 cases percentage due to close contacts at workplace as well as those in households. Distinguishing characteristics of the third period of the second stage of the epidemic (June 29-July 26) were maximal COVID-19 detection rates, rise in proportion of community-acquired pneumonia, severe cases and high mortality rates. Downward trend of incidence rates were registered during the third stage of the epidemic (July 27-September 6). Most of the restrictive measures were removed during this stage that lead to resumption of COVID-19 incidence growth rates in the 4th stage of the epidemic (September 7October 4). Termination of self-isolation for citizens aged over 65 and start of educational process facilitated greater involvement of population of advanced age and children aged 7-17 years. Most peculiar manifestations of COVID-19 in the Khabarovsk krai were substantial contribution of community-acquired pneumonia, growth of which was associated with late presentation for medical help during the period of observation. A tendency of increase in number of severe forms of the infection and mortality rate as well as considerable differences in incidence levels in different territories of the Khabarovsk krai were revealed.

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