If the results of the tests – carried out on the same day – may surprise, it is however not surprising: the antigenic tests are 70% reliable and there can be false positives.
- Elon Musk performed four antigen tests on the same day: two were positive, and two were negative.
- This is explained by the false positives that can occur with antigenic tests, which are 70% reliable.
Two out of four, it doesn’t really help to see clearly. The American billionaire Elon Musk, boss of the Tesla companies, shared on Twitter an anecdote that happened to him recently. In his message, he explains that he did four antigen tests on the same day to find out if he had Covid-19. Of the four tests, two came back positive and two came back negative.
Something extremely bogus is going on. Was tested for covid four times today. Two tests came back negative, two came back positive. Same machine, same test, same nurse. Rapid antigen test from BD.
— Elon Musk (@elonmusk) November 13, 2020
In his message, the billionaire specifies that the four samples were taken with antigenic tests, that they were all read by the same machine and that it was the same nurse who took care of them.
Do an RT-PCR test to confirm
If this may seem strange at first glance, the situation is not exceptional. Antigen tests shine by their speed compared to RT-PCR tests (half an hour compared to several hours for RT-PCR). However, their fields of action are different, since the antigenic test looks for the proteins produced by Sars-CoV-2 while the RT-PCR test detects the genetic material of Covid-19.
With 100% success for the RT-PCR test against 70% for the antigen test, the RT-PCR test is more reliable, which is why Elon Musk’s two negative tests do not call for worry. In the event that false positives occur with antigen tests, it is advisable to perform an RT-PCR test to dispel doubt.
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