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Objective. To perform an interim analysis of epidemiological parameters of COVID-19 related to contacts and secondary cases of infection in the Russian Federation. Materials and methods. We analyzed 190,856 primary COVID-19 cases and 146,996 people who had been in contact with them. We used some data of monitoring performed by the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing in January–June 2020. We characterized the foci of infection and people who had contacts with primary COVID-19 cases and secondary cases of infection. Results. Just over half (50.02%) of study participants who had contacts with COVID-19 contacted with primary patients with mild disease, whereas 45.40% of individuals contacted with patients with moderate disease and 4.58% of individuals had contacts with patients with severe disease. Patients with mild COVID-19 interacted with more people, which resulted in a greater number of secondary cases of infection. The highest proportion of both primary COVID-19 patients and people who had contact with COVID-19 was observed in the age group of 41–64 years (44.42% and 44.51%, respectively). Approximately one third of COVID-19 patients and people who had contact with COVID-19 were 18 to 40 years old (30.20% and 34.21% respectively). The proportions of children aged 0–6 years and 7–17 years among COVID-19 patients were 2.70% and 4.02%, respectively; the same proportions among those who had contact with COVID-19 cases were 1.94 and 3.13%, respectively. Household contacts were the most common ways of COVID-19 transmission in all age groups. Patients aged between 40 and 64 years played the most significant role in the transmission of this infection in different foci. Individuals from this age group comprised 42.02% of patients infected in social institutions, 43.40% of those who had household contacts, and 47.70% of those infected at work. Conclusion. Patients with mild and moderate disease aged 18 to 64 years had the highest number of contacts and, therefore, caused the highest number of secondary cases of infection. Household contacts played the most important role in COVID-19 transmission in all age groups. Among people aged 18 to 64 years, COVID-19 transmission at work was also important. In all foci of infection, the majority of patients were in the age group of 40–64 years. Our findings can be used to optimize the preventive measures for COVID-19. Key words: epidemic process, age groups, severity, contacts, COVID-19, Russia, household contacts

Active epidemic process in Russia started in the March, 2020 after beginning the local transmission. At the end of June approximately 650 thousands COVID-19 cases were recorded in Russia. Aim of study: epidemical characteristics of patients with COVID-19 in Russia Materials and methods: statistic analysis of database of COVID-19 in Russia during the first half of 2020. Majority of cases in a group aged 0-17 years old was mild. Patients > 65 years and above were registered with a moderate and severe forms of COVID-19, what shows that this group needs a special attention. The biggest part of all the cases was in a group of people of employable age. This fact shows that control of restrictive measures has to be performed as a main stream in this group. In case of delayed initial medical service COVID-19 had more moderate and severe forms.

Background: Understanding the impact of geographical aspects and population density on the incidence rate (IR) of respiratory infections in Russia is necessary for successful control under the epidemic. Aim: to estimate the increase in IR of respiratory infections in 2020 compared to the same period of 2016-2019 Materials and methods: a retrospective study of IR of COVID-19, ARI, influenza and community acquired pneumonia (CAP) in summarily (respiratory infections and COVID-19 morbidity) in the first half of 2020 in comparison with morbidity of ARI, influenza and CAP (respiratory infections morbidity) the same period of 2016-2019 in 85 regions was performed. Additionally the influence of climate on COVID-19 morbidity were estimated. Results: The highest excess of respiratory infections and COVID-19 morbidity in 2020 versus the average respiratory infections morbidity in 2016-2019 was observed in Buryatia-107.61%; Zabaykalsky Krai -134.09%; Tuva – 166.34%; the Kaliningrad region – 1023.41%; the Republic of Altai – 1212.78%; Dagestan – 2030.27%. Buryatia, Tuva, Altai and Zabaykalsky Krai are located next to the China, and also border each other. The Kaliningrad region borders on the EU countries. Dagestan has a maritime border with 3 states, including Iran, where the epidemic COVID-19 began earlier. In 43 of the 85 regions of Russia, this excess was 10-50%; in 35 subjects varied from 50% to 100%. The correlation between the incidence of COVID-19 and the population density in the regions was weak (r=0.26). The air pollution, has also a weak relationship (r=0.26) to the incidence rate. Moderate relationship was observed between the severity of negative temperatures in winter and the level of morbidity(r=-0.51). Milder climate probably contributed to the longer persistence of the virus in the environment and social activity. Conclusion: Russian regions bordering the PRC, the EU, Central Asia and the Middle East demonstrated the highest IR of influenza, ARI, CAP and COVID-19in summarility in the first part of this year versus the morbidity of influenza, ARI, CAP in average in first half of 2016-2019. IR of COVID-19 has weak correlation with population density and air pollution and moderate negative correlation with winter temperature.

Введение: в разных регионах Российской Федерации (РФ) отмечены различия в интенсивности эпидемического процесса COVID-19, что, возможно связано с географическим расположением, климатом и плотностью населения Цель исследования: изучить рост заболеваемости респираторными инфекциями в 2020 г. в сравнении с 2016-2019 гг. в РФ в зависимости от географического расположения субъектов РФ, климата и плотности населения. Материалы и методы: сравнительный анализ суммарной заболеваемости COVID-19, ОРВИ, гриппом и пневмонией за первое полугодие 2020 г. в сравнении с заболеваемостью теми же респираторными инфекциями (за исключением COVID-19) в аналогичном периоде 2016-2019 гг. в РФ на основании данных мониторинга Роспотребнадзора. Дополнительно оценивалась взаимосвязь респираторных заболеваний в первом полугодии 2020 года с географическими и климатическими параметрами с применением методов регрессионного анализа. Выводы: Географическое расположение субъектов РФ, пограничных с КНР, странами ЕС, и Ближнего Востока влияло на прирост заболеваемости и составило от 33,78% до 1445,00%. Плотность населения в регионах, в свою очередь, слабо взаимосвязана приростом заболеваемости респираторными инфекциями. В первую очередь на рост заболеваемости влияли не климатогеографические характеристики региона, и не плотность его населения, а, вероятнее всего, жесткие ограничительные меры и контроль за их соблюдением. Например, принятые в Москве меры привели к тому, что, несмотря на наибольшую плотность населения, прирост заболеваемости уступает многим другим регионам. А в субъектах с высоким уровнем прироста заболеваемости плотность населения не отличается высокими значениями.