Over the past year we have been forced to remain indoors or to be able to go out only with a mask due to a lethal virus, commonly called Covid-19, which is infecting people all over the world, with serious consequences. But where did this virus originate from? And how did it spread so fast?

The SARS-CoV-2 virus, or Covid-19, belongs to the Coronavirus genus, a group of RNA viruses which also includes Sars and Mers. Viruses of this category are present in nature in bats, from which they can then pass to other mammals. In the case of the Covid-19 virus, a study by Chinese researchers has identified the origin of the virus in a natural recombination event between two different coronaviruses, one of the bats and one of the pangolin, which simultaneously found themselves in the same host and have mutually “exchanged” parts of the genome. From this exchange of genetic material, a new virus would have been born that could also infect the cells of human beings. Despite this research, at the moment, the evolutionary path of the SARS-CoV-2 coronavirus and the animal species that transmitted the virus to humans remain uncertain.

The only certainty we have is that the first cases of infection caused by Covid-19 were recorded on December 31, 2019 in Wuhan, the capital of the Chinese province of Hubei. The first outbreak of the infection may have been the city’s fish market, which favored the spread of the virus due to the presence of a large number of people, proximity to wild animals and the slaughtering of live animals. Consumption of raw meat may also have contributed further to increasing the risk of spread.

As soon as the circulation of this virus was discovered, the Chinese government immediately initiated extraordinary measures, with the aim of containing the infection (by placing Wuhan and other cities under quarantine), thanks to which until the end of January most cases remained confined to Chinese territory. However, on 18 February 2020, the first secondary transmission in Italy was recorded in Codogno, Lombardy, i.e. a patient infected on the Italian territory. Shortly after, a second outbreak was also discovered in Vo ‘, Veneto, which confirmed that the virus was spreading freely also in Italy and subsequently throughout the world.

This expansion can be explained by the fact that Wuhan, being a large metropolis, has an airport that has daily connections with foreign countries, or by the position of China which is at the center of many migratory routes of birds that may have transferred and spread the virus across the territory. However these are only hypotheses that haven’t been proven, yet.

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