Question asked on 10/08/2020
The analysis of the results of RT-PCR tests that measure the viral load of Sars-CoV-2 in a patient has been the subject of much debate in recent months. These tests make it possible to detect the RNA (molecule close to DNA) of the virus in the patient’s nasopharyngeal sample, thanks to a process of amplification of the genome by cycles. The techniques available make it possible to target between 1 and 3 viral genes. The more cycles it takes to make the RNA noticeable (this value is generally between 10 and 45) the less virus there is in the sample taken. This threshold cycle (CT) from which a result is positive has been at the heart of the debates for several weeks.
In the United States, an article from New York Times published at the end of August cast doubt on the usefulness of these tests carried out around the world in the fight against the Covid-19 epidemic, as we explained in a previous answer. With a value of
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