It seems the alleged SARS-CoV-2 virus (allegedly responsible for the COVID-19 pandemic) has not been "directly" isolated (difference between direct and indirect isolation is explained here). Apparently it has not even been purified.

The information I have is this link:

COVID19 PCR tests are scientifically meaningless

It is worth mentioning that the PCR tests used to identify so-called COVID-19 patients presumably infected by what is called SARS-CoV-2 do not have a valid gold standard to compare them with. This is a fundamental point. Tests need to be evaluated to determine their preciseness — strictly speaking their “sensitivity” and “specificity” — by comparison with a “gold standard,” meaning the most accurate method available. As an example, for a pregnancy test the gold standard would be the pregnancy itself.

Jessica C. Watson from Bristol University confirms this. In her paper “Interpreting a COVID-19 test result”, published recently in The British Medical Journal, she writes that there is a “lack of such a clear-cut ‘gold-standard’ for COVID-19 testing.” But instead of classifying the tests as unsuitable for SARS-CoV-2 detection and COVID-19 diagnosis, or instead of pointing out that only a virus, proven through isolation and purification, can be a solid gold standard, Watson claims in all seriousness that, “pragmatically” COVID-19 diagnosis itself, remarkably including PCR testing itself, “may be the best available ‘gold standard’.” But this is not scientifically sound.

It would be a similar case to alleged HIV.