Hello and welcome to HCM,ELISA
is a screening test for HIV
1 & 2.
It detects HIV 1 antigen in serum by antigen-antibody reaction.
This test detects the p24 antigen of the HIV virus.
However, this test can come out to be negative if the patient is in window period.
Window period is the time when the test is false negative.
A period of atleast 3 months should elapse before a repeat test is done.
If the ELISA test comes to be positive after 3 months, RPR test is done.
RPR test is confirmatory test for HIV infection.
Thanks and take care
Dr Shailja P Wahal