He pointed to the fact that spillover events  when viruses jump from animals to humans  are common in nature, and that scientists already know of two similar beta coronaviruses that evolved in bats and caused epidemics when humans were infected, SARS1 and MERS. While the closest known viruses to Covid-19 have been found in bats, the 'evolutionary distance' between them is thought to be 'several decades'. Questions of origins and questions of disease control are not the same thing once human-to-human transmission has become common, said Deborah Seligsohn, an expert in environment and public health at Villanova University. HOW IMPORTANT IS IT TO UNDERSTAND THE ORIGIN? In the case of Severe Acute Respiratory Syndrome (SARS)  a disease caused by a beta coronavirus, like the current coronavirus  researchers first identified the virus in February 2003.
Researchers know about two kinds of virus.
( z0 know :ARG0 ( z1 person :ARG0-of ( z2 research ) ) :ARG1 ( z3 virus :mod ( z4 kind :quant 2 ) ) )
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    :ARG0 (z1 / person
              :ARG0-of (z2 / research-01))
    :ARG1 (z3 / virus
              :mod (z4 / kind
                       :quant 2)))
Researchers know about two kinds of virus .
z1 :ARG0-of z2
z0 :ARG0 z1
z4 :quant 0
z3 :mod z4
z0 :ARG1 z3