This is an interesting study. This link is to the summary. There is a link there to the full study. 600 people with active disease of over 2 weeks completed a survey to find out just what people are experiencing with the illness. I find the following most interesting:
● Early testing is crucial, and questions remain around test accuracy: Despite all respondents showing COVID-19 symptoms, 47.8% were either denied testing or not tested for another reason. The main difference between respondents who tested positive and those who tested negative was how early in their illness they were tested (on average day 10 for those testing positive, and day 16 for those testing negative).
Furthermore, the only difference in symptoms between these groups is that those who tested positive reported loss of smell and loss of taste more often, even when controlling for testing time.
It suggests that the test being used is testing for what ever caused the loss of smell/taste. But, if that is not you, you test negative. It also appears that the longer you are into the disease, the less likely you will test positive.
Both of those combined suggest the need to test for a different marker of the virus as what is being tested for does not react the same in too many cases and may even pass away thus no longer being present.