Results of analysis of phylogenetic, virological, epidemiological, ecological, clinical data of COVID-19 outbreaks in Wuhan, China (PRC) in comparison with SARS-2002 and MERS-2012 outbreaks allow to conclude: - the etiological agent of COVID-19 is coronavirus (2019-CoV), phylogenetically close to the SARS-CoV, isolated from human, and SARS-related viruses isolated from bats (SARS-related bat CoV viruses). These viruses belong to the Sarbecovirus subgenus, Betacoronavirus genus, Orthocoronavirinae subfamily, Coronaviridae family (Cornidovirinea: Nidovirales). COVID-19 is a variant of SARS-2002 and is different from MERS-2012 outbreak, which were caused by coronavirus belonged to the subgenus Merbecovirus of the same genus; - according to the results of phylogenetic analysis of 35 different betacoronaviruses, isolated from human and from wild animals in 2002-2019, the natural source of COVID-19 and SARS-CoV (2002) is bats of Rhinolophus genus (Rhinolophidae) and, probably, some species of other genera. An additional reservoir of the virus could be an intermediate animal species (snakes, civet, hedgehogs, badgers, etc.) that are infected by eating of infected bats. SARS-like coronaviruses circulated in bats in the interepidemic period (2003-2019); - seasonal coronaviruses (subgenus Duvinacovirus, Alphacoronavirus) are currently circulating (November 2019 - January 2020) in the European part of Russia, Urals, Siberia and the Far East of Russia, along with the influenza viruses A(H1N1)pdm09, A(H3N2), and capital VE, Cyrillic, as well as six other respiratory viruses (HPIV, HAdV, HRSV, HRV, HBoV, and HMPV).