For those that think we can test our way out of this crisis, I offer the following facts. If after reading, you don’t believe me, go google some of the terms and read up on some epidemiology.
Firstly, consider that no test is perfect. No test will correctly diagnose either a negative or a positive in all cases.
Consider a test that has 95% sensitivity and 95% specificity. Some PCR tests (the one where they stick a swab up your nose) m-a-y approach this level of accuracy. Antigen tests are not as accurate. Sensitivity means the percentage of cases a test correctly identifies as positive. Specificity means the percentage of cases a test correctly identifies as negative. In reality these two figures will be different, but for arguments sake I have made them the same.
Where a disease has low prevalence in the population (as with SARS-CoV-2 right now) even with a highly accurate PCR test with the sensitivity and specificity mentioned above, the probability of a positive test (called the positive predictive value) being correct is as low as 50%.
Testing has a place, but it’s not the be all and end all.