[The patterns of seasonal outbreaks of acute respiratory diseases]

The COVID-19 epidemic cause is considered to be "patient zero" contaminated by coronavirus infection in December 2019 in China. However, accumulated facts dispute this version of events. The first infected patient appeared in September in the United States, in December - in France. in November-December pneumonia of similar severity raged in Russia. It is difficult to explain numerous outbreaks of simultaneous contagions in isolated staffs, including military garrisons. In most of healthy adults' antibodies to coronavirus are found. The most of infected patients have no symptoms of disease. To explain these paradoxes ecological hypothesis is proposed - humanity and coronaviruses have been interacting evolutionarily for thousands years in system of biogeocenosis, periodically confronting under influence of cyclical ecological processes. The purpose of study is to investigate relationship between mortality of acute out-of-hospital pneumonia, coronavirus ones included, and cyclical fluctuations of environmental conditions. The primary material was obtained from data of Rosstat, international information bases, results of scientific studies. The classic methods of medical statistics were applied. The summer solstice (June) was used as reference point for estimating dynamics of monthly mortality in 2015-2020. The analysis of dynamics of mortality of pneumonia averaged for 2015-2020 revealed three epidemic waves with peaks in October, January, and March. Such cyclical pattern was consistently reproduced for particular years in 2015-2020. The first wave always was the lowest one. When the second wave exceeds the third one, increase in mortality in February and March was the smallest one. The greatest epidemic losses were established at the plateau. In 2020, the rate of coronavirus infection in the world coincides with the established cyclicity. The stable reproducibility of three peaks of mortality in same months testifies their regular character. The cause of all this may be the cyclicity of ecological interactions between coronaviruses and human population.