Elon Musk says he’s tested positive and negative for COVID-19

[Los pollos hermanos]

Elon Musk announced on Twitter he has tested both positive and negative for COVID-19 after taking four rapid antigen tests.

 

[hirashgeff]

කමක් නෑ බන් දිලිත් ගේන එක රැන්ඩම් වැඩකරලා කොවිඩ් උන් අල්ලලා දෙයි...

 

[Los pollos hermanos]

 

[batwise]

 

[imhotep]

Though I didn't watch it full, I did watch the Part where Dr Cowan talks about the PCR. What he said is correct but not the whole picture. On a previous post on a Covid Megathread, I have explained in detail how a RT-PCR is done. The Ct value does play a part. The Ct is what's known as the Cycle Threshold - is the number of Cycles needed for the fluorescent signal to cross the threshold above the background. A PCR is done usually to a max of 40 cycles...
Cts < 29 are strong positive reactions indicative of abundant target nucleic acid
Cts of 30-37 are positive reactions indicative of moderate amounts of target nucleic acid
Cts of 38-40 are weak reactions indicative of minimal amounts of target nucleic acid which could represent an infection state or environmental contamination.

So a high CT value is dubious. That's what Dr Cowan says but vaguely. You cannot rely on Ct after 37 at all. In which case you do another PCR test a few days later. These can be false positives.

A team of scientists recently did a study more than 3000 cases the graph below shows the results. Ct against infectvity. They did a PCR test and also they did a viral culture using the same swab to independently grow the virus to confirm. The number of Samples N is the PCR test, The number of Samples n is the Virus detected in the culture.
One can easily see at high Ct values the results are inaccurate. The Global percentage value graph is 100% at low Ct values and then keeps on falling down to zero at Ct around 36. This is well known but only probably not known by an average person.

Also studies done in several countries (most recently in Brazil) has shown that nearly 35% of patients Ct value of 25 or below were more likely to have severe disease or die. So things tend to be a bit more complex than explained by a simple video.