√ There will always be false negatives and false positives.
√ The concern with COVID testing is what proportion are false negatives.
In a large population ie. 50,000, even 1% false negatives infers great risk.
√ The blue line on the graph depicts the probability of a true positive nasal test.
The virus detection rate increases as the day of first symptoms approaches.
Then declines over the course of many weeks.