Coronavirus infections are a group of diseases caused by viruses of zoonotic origin, characterized by polymorphic clinical evidence, adverse clinical and epidemiological consequences, widespread prevalence among animals and humans. Currently, the disease has acquired a predominantly anthroponotic character.
Despite the more than 50-year history since the discovery of the pathogens of coronavirus infection, the epidemiology of human diseases remains insufficiently studied. This primarily concerns the causes of the appearance, preservation of the virus, the dynamics of the emergence and spread of infection among people. The appearance of severe acute respiratory syndrome in people in 2002-2003 and Eastern Mediterranean Respiratory syndrome in 2012 and studying them have not radically changed our understanding of the key problems of epidemiology. The sudden emergence of the "new" COVID-19 coronavirus infection in China and its spread in the world caused the strongest destabilization of the economy, education systems, healthcare of all countries in the world, social tension in society.
Today, there are 7 known strains of coronaviruses that cause human diseases:
1. Сoronavirus (HCoV-NL63, New Haven coronavirus)
2. Сoronavirus HKU1
3. Coronavirus NL63 (HCoV-NL63, New Haven coronavirus)
4. Сoronavirus HKU1
5. Severe acute respiratory syndrome coronavirus (SARS-CoV) 2002-2003 г
6. Middle East respiratory syndrome-related coronavirus (MERS-CoV), also known as the new coronavirus of 2012 and HCoV-EMC
7. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), previously named as 2019-nCoV , and now as СОVID 2019.
The first four strains cause mild acute respiratory diseases that, as a rule, remain etiologically undeciphered, the rest are famous coronavirus diseases with varying degrees of severity and adverse consequences.
The story of COVID-19 started in Wuhan, Hubei Province of central China, where cases of pneumonia of unknown aetiology were detected in late December 2019. The sick residents worked or bought food at the local market to sell animals and seafood. The official announcement of an outbreak of "atypical pneumonia" of unknown aetiology appeared on December 31, 2019 [1], although the first cases had been detected in China since December 8, 2019 [2,3]. The Chinese authorities informed the WHO about an outbreak of unknown pneumonia on December 31, 2019, and the city of Wuhan was quarantined. The isolation of the coronavirus, the spread of the disease on the territory of China, the importation of the disease to other countries and territories allowed the WHO Emergency Committee on January 30, 2020, to recognize the outbreak caused by the new coronavirus as a public health emergency of international concern [4]. Chinese scientists isolated the new coronavirus, originally named 2019-nCoV, and established 79.5% of the association of its genome sequence with the SARSCoV virus, which causes severe acute respiratory syndrome [5]. The new disease got its name, COVID-2019, on February 11, 2020. By the proposal of the WHO Committee of Experts, the coronavirus infection caused by the COVID-19 virus has been classified as a pandemic disease.