With todays ultra sensitive modern ELISA tests, what use is the western blot for hiv? A few months ago I received a weakly reactive cmia HIV ag/ab test, a 4th generation HIV combo test, and this was followed by a negative western blot and a negative p24 t

False-positives. Screening tests are designed to be highly sensitive so they don't miss anyone with the disease. However, they can be so sensitive that they occasionally give a false-positive result. That is, the test appears positive for someone without the disease. The western blot, being time consuming and extra cost, is only used to make sure a positive is really a positive. Talk with your doc for more info.
It . It seems very unlikely that the cmia HIV ag/ab test is indicative of true infection with only a weak reaction and 2 negative western blots and p24 antigens and 2 other negative antibody screens.7 months after exposure. The only way this could be is if you had acquired a strain of HIV that only the cmia HIV ag/ab test could detect. This seems highly unlikely. A cross reacting substance in your blood that this test reacts weakly to is much more likely. The only further test to confirm this that is easy to get is the pcr however.