COMMENT FROM MEDICAL INDUSTRY
Let’s also keep in mind that our tests are not perfect, and extensive testing for a disease with a very low incidence will lead to many more false positive results, than true positive results.
If we carry out extensive screening for COVID-19, we are at even greater risk of our tests failing us. Assuming about 15,000 infections in a country of about 300,000,000 people, that gives an approximate incidence of 0.005%. The most accurate test has a specificity of about 95%. This means that if we carried out population-wide screening, that 99.9% of the confirmed positive test results will be a false positive result, meaning that approximately 14,999,250 people tested will have a positive test result, but do not have the disease, meanwhile only 14,250 of the 15,000 who have the disease will have a positive test result.
This is why we only want to test those individuals who have a possibly significant history of exposure, and appropriate symptoms of the disease that we are testing for.
Thanks for listening,
LB