No Test is Perfect

√ 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.