How do false-positive results happen in an HIV test?

How do false-positive results happen in an HIV test?

Charles Farthing (Chief of Medicine, AIDS Healthcare Foundation) gives expert video advice on: What does it mean to be HIV positive?; Is a positive HIV test result a 'death sentence'? and more...

False-positive results are possible in an HIV test. In medicine, in any antibody test, there may be a similar protein that you've been exposed to that may look like an HIV antibody; it isn't an HIV antibody, but it may trigger the test as positive. So that's why the ELISA test has a small rate of false-positive results. The more expensive Western Blot antibody test looks at multiple antibodies to different components of the virus. If you have multiple antibodies to HIV, then one can be sure that you are infected.