https://asm.org/Articles/2020/April/False-Negatives-and-Reinfections-the-Challenges-of

https://www.asianscientist.com/2020/04/features/covid-19-diagnostics-explained/

I would say the Gold Standard test doesnt necessitate it being 'perfect', just that it is the best current test we have that we can benchmark others on. Usually they are quite invasive but in this case not so much. There are always limitations to any test and the key is understanding them in the final interpretation. As science evolves new gold standards emerge and replace our old best methods.

For Covid, we are early in the development process. rtPCR is the best we have for detection currently but like everything we just need to know the limitations and how to interpret things like a negative test. Good question though

Hi

Please check the following work. It describes the process in details. I believe it will help you.

https://www.raybiotech.com/covid-19-rt-pcr/

Regards

Comparing with the three strains, most suspicious fact is the death rate is high due to the secondary infection or Chronic diseases. It may highly damage the immunity system.