With the discovery that the SARS disease was being caused by the coronavirus laboratories started work on diagnostic tests to be able to see whether a person had contracted the coronavirus. With effective diagnostic tests there would be no need for quarantine of healthy people and instead isolation of infected people could happen.

Two different tests were produced, test A and test B.

No medical test is perfect. All tests have problems with sensitivity and specificity.

Sensitivity is also called the true positive rate. It is the percentage of people with the disease that the test recognises as having the disease.

If a test was 90% sensitive then if people with the disease took the test it would recognise that they had the disease correctly 9 out of every 10 times. However, 1 out of every 10 tests it would tell somebody who had the disease that they didn’t have the disease and they would not be isolated.

Specificity is also called the true negative rate. It is the percentage of healthy people that the test recognises as not having the disease.

If a test was 90% specific then if healthy people took the test, 9 out of every 10 tests they would be correctly identified as not having the disease. However, 1 out of every 10 tests it would tell somebody who was healthy that they had the disease and they would be put into isolation even though it was not actually necessary.

On the next page is the data from the two tests