Different variants of Sars-Cov-2 were developed in England, South Africa, Brazilia and Japan. They are at the basis of an increase in contagiousness.
Sars-cov-2, responsible of the covid-19 pandemic, has several thousand variants. It is a frequent and natural phenomenon. In the case of the British, South-African or Brazilian variants however, copying errors allowed them to be more contagious.
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N501Y and E484K , two particular mutations are currentlty monitored. the first is suspected of making the coronavirus more contagious whereas the second gives potential resistance to to variants that carry it.