Let’s now hear the story of Peter. He arrives in hospital to do an HIV test, which is part of his immigration exam to take up a job opportunity in a new country. The test protocol is an ELISA- Antibody test confirmed by Western Blot. This protocol is well validated and its characteristics for the test combination are: SE = 99.99%, SP = 99.99%

A week later he gets a letter telling him that the result is positive. He is very surprised by this and starts looking at the internet to learn what this positive result means. He finds the following:

“A positive result means antibodies to HIV were found in your blood. This means you have HIV infection. You are infected for life and can spread disease to others.”

Is this really true?
How confident can Peter be in the positive test result?