Hi Curious, Yes, sorry our test has a clinical SENSITIVITY of 99.7% and a clinical SPECIFICITY of 99.9%. On average 997 positive cases will be detected in every thousand tests. Sorry for my previous post and thank you for correcting me. Kindest regards, Becky

I'm sorry but can I ask, in relation to your post, it says on your website that it has clinical sensitivity of 99.7% not 99.9%, which is the specificity? Effectively 3 out of every 1000 hiv positive people taking test may get false negative results with 99.7% sensitivity, including outside the window. Is this correct?

Hi Nicholas, The BioSURE HIV self test has a clinical sensitivity of 99.9% so essentially every 1 in 1000 negative results are false. The window period is 12 weeks, anyone is welcome to test at any time during this window period but we always recommend to retest at 12 weeks for a conclusive result. False negative results are more common when testing inside the window period as if a persons body has not produced antibodies in response to the virus, the test will not be able to detect this and therefore may give a negative result when in fact the person is HIV positive. False negative results have also been reported when a person is taking antiretroviral treatment, such as PEP or PrEP. This is due to the ART medication inhibiting HIV viral replication and subsequently lowering the viral load - this in turn reduces the production of antibodies and therefore the test will not be able to accurately give a reliable result. We recommend to wait 12 weeks after finishing any course or PrEP or PEP to test. Again, the rate of false negatives is 99.9% for the BioSURE HIV self test. I hope this information helps. Becky

What percentage of a false negative is due to it being within the window period? What are the other possible causes of a potential false negative and how likely are they to occur?

Hi Learning, The likelihood of both tests (performed well outside of the window period) being false negatives is around 1 in a million. Usually only false negative results occur when users test inside of the window period. I would be very confident in your negative results and hopefully you can try to put this behind you and move on. Kindest regards, Becky