Hi Jada, Since your possible exposure was in 2016, any BioSure test taken 12 weeks after this initial exposure is accurate and conclusive. The 6 month time period of when you took the BioSure self-tests is a sufficient period of time for your body to have produced enough antibodies to the virus for both of the tests to be able to detect a result. Although I cannot comment on the accuracy or window period of the p24 or PCR RNA test, since your exposure was so long ago, I would say that both of these test results were accurate and conclusive. If you wanted to be sure, you could take another BioSure test now. A negative result now would be 100% conclusive and it may help to put your mind at rest. Since your possible exposure was 4 years ago, if you were to be positive, the test would very clearly show a strong, dark test line which would be a very clear indication of a positive status. However, I would say that given your previous negative test results, it is very very very unlikely that your result would change now. Kindest regards, Becky, BioSURE UK LTD