Talking about home testing for HIV

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Information about the reliability of the test

Information about the reliability of the test seems unavailable. The publicity says “BioSure HIV Self Test is over 99.7% accurate” but without explaining what this means.

That three HIV-free people in every 1000 HIV-free people tested will show up as positive? That results will be indeterminate in 0.3% of cases?

7 Responses

Gary Carpenter, BioSure (UK) Limited
 Work on 28th February 2017

Dear Hello1 The test is very robust to slight errors in performance. Pushing the test into the buffer pot after waiting a while will not cause the test to fail. The key thing is that the line towards the top of the test strip appears as per the instructions for use. This upper line shows that the test has worked. 1 line on the test is a negative result and two lines would be positive. I hope that this helps to answer your question. If you have any other questions you can email me directly at Kind regards Gary Carpenter BioSure (UK) Limited

 Used on 26th February 2017

I did the test but didn't completely insert the blood into the bottle and waited 15mins then fully inserted and it showed positive. Is this reliable?

Gary Carpenter, BioSure (UK)
 Work on 13th November 2016

Hi Mountain Thanks for your question. The BioSure HIV Self Test works by detecting antibodies to HIV rather than directly detecting the virus itself. Each person creates these antibodies at slightly different times post infection. After 10 weeks around 97% of people will have produced the antibodies required. I hope that this helps. Kind regards Gary Carpenter BioSure (UK) Limited

 Used on 11th November 2016

Hi I did the biosure test which turned negative but I performed the test 11 days before the 3 month mark. How reliable is the test just days before the suggested window period?

 Work on 08th October 2015

Hi, thanks for your question. The answers is unfortunately not simple. The probability of certain types of failure is not independent, but others are. In fact, the possible causes of failure can be dependent on the person taking the test or a function of the test itself or a combination of both. For us the most important (most severe harm risk) failure would be a False Negative result. This occurs when the test result is negative, but the person testing is actually positive. In this instance there are three probable causes: the test is used inside the window period, the user misreads the test result as negative when it is actually positive or the test has been manufactured incorrectly. In a series of two tests, the probability of failure for the first instance would not be reduced by performing a second test. For the other two scenarios the probability of failure would be reduced by performing the second test. So, if you performed two tests after the window period (3 months) has elapsed, the probability of two negative test results both being wrong is, as you pointed out, incredibly small. I hope that this helps to put your mind at ease.

 Used on 07th October 2015

Thank you for the information. After opening the pack I found the information, but I had wanted to understand the question of reliability before opening the pack. One more question: For a given person, are failures of the test independent? Or, if the test fails for a particular person, is a second test also likely to fail for them? If failures are independent, then presumably a person with HIV would not be detected by two tests in succession with a probability of (3/1000) × (3/1000) - about 1/100,000 (certainty for practical purposes). Thank you again for your help.

 Used on 02nd October 2015

Hi, thanks for your post Extensive research has proven our HIV self test is extremely accurate when performed correctly, with similar accuracy to a pregnancy test. The control line is a sample control line, so it will only react and become visible if the test is done correctly with enough human blood. • It has a proven clinical sensitivity (if a person has HIV how often the test will be positive) of 99.7%, this means that on average 997 in every 1,000 positive results will be correct. • It has a proven clinical specificity (if a person doesn’t have HIV how often will the test be negative) of 99.9%, this means that on average 999 in every 1,000 negative results will be correct. We have included this in the packaging and on the website so I’m sorry it has not been clear to you. I hope this helps but please let us know if you have any other questions.

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