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4th Generation EIA vs. HIV Home-test

Question: 

Hello,

I took bought an online hiv test to take at home and it came back "reactive" 5 weeks after I slept with someone.

The online company told me to go to my nearest STI clinic to take anther test. The STI clinic gave me the 4th generation ag/ab test six weeks after exposure which came back negative. I was then told to come back 4 weeks later to retake the test, I done this and it came back negative again. The 2nd time I took the 4th generation test would make it 10 weeks after I slept with that person.

Would you say I am HIV negative and I should stop worrying? I still feel worried and I feel like i have symptoms but Im not sure if it's the stress of worrying that may be causing them.

Also would you be able to tell me what can cause a false positive result to happen? I spoke to the online company that I first took the test with and they said that false positives are always a risk when taking the test.

Many Thanks

Answer: 

Hello,

Thank you for your inquiry. From what we gather from the question, you were asking about the conclusiveness of two negative 4th Generation EIA "DUO" Test result versus a positive HIV home test.

From your question you stated that a 4th Generation EIA "DUO" test was performed 6 weeks post-exposure as well as 10 weeks post-exposure. After 6 weeks, most HIV specialists would consider the 4th Generation EIA "DUO" test conclusive because the test can detect HIV infection in 99% of people after this amount of time (1). Although a false-positive outcome from a home test kit is rare, it has been cited in the literature (2). Home-based HIV testing may lead to a false-negative result, thus a lab-based test should be favoured when comparing the two (3).

References:

1) http://www.catie.ca/en/fact-sheets/testing/hiv-testing-technologies

2) https://sti.bmj.com/content/81/4/359.1

3) http://www.catie.ca/en/pif/spring-2014/hiv-home-based-testing-potential-benefits-and-ongoing-concerns

Recommendation: No need for HIV test with the scenario provided, refer to a physician for other health related questions.

Regards,

AIDS Vancouver Helpline/Online, Marie