Q: I know that in ELISA TEST FOR HIV there can be a false postive test. Is it possible that there may be also a false negative test? If so, can we rely on an ELISA test AFTER 6 months of window period? And also, can the testing lab be hiding the positive result and giving a negative result? Have you heard of any case like that after the window period.

A:After the window period a negative test, even one, is definite proof that there is no HIV infection. False negatives are extremely uncommon in situations such as in India where overall prevalence is very low. However, false positive tests are quite common and therefore repeat tests should always be done before labeling a person as positive. And why should any Laboratory hide results and purposely give negative results. If you use good reliable laboratories you have no reaason to suspect the results.