Hi Anxiety girl, The BioSure self-test is a second generation test and has a 12 week window period. This means that your body will have had to produce detectable levels of antibodies before the test can detect a conclusive result. At 4 weeks (28 days), 50% of people will have produced enough antibodies for the test to be able to detect an accurate result, however everyone produces antibodies at different rates so there really is no way of knowing whether you are one of these. ELISA antibody tests are usually fourth generation and have around a 4 week window period, however I cannot comment on your result as I have no further information regarding this. I would recommend to retest at 12 weeks if you wish to use a BioSure self-test to be sure of your result, as at 12 weeks your result would be conclusive. I hope this helps, if you have any other questions please feel free to leave them in the thread below. Kindest regards, Becky, BioSURE UK LTD