Avatar universal

HIV-1 RNA Qualitative Test reliability after 18 days and other questions

I recently had a potential exposure. After 18 days I had tests performed at Labcorp. I opted to have the rapid test performed. My lab results show this test is called "HIV-1 RNA Qualitative". Result for this test was NEGATIVE.

1. My first question is how reliable is the result of the "HIV-1 RNA Qualitative" test after 18 days. Can I breathe easier?

2. My second question is regarding the "HIV 1/O/2 Abs-ICMA" test and "HIV 1/O/2 Abs, Qual". Both were negative but I understand that 18 days is not reliable for this and that I should wait until the 4 week mark. Is this a correct understanding? Is this a 4th generation test which can be conclusive after 4 weeks?

Thank you for your time.
3 Responses
239123 tn?1267647614
Welcome to the forum.  Thanks for your confidence in our services.  I'll go directly to your questions.

1) The RNA and DNA direct tests were not designed for the purpose of early HIV diagnosis.  They are commonly used that way, but there has been little research on test performance in this setting.  The result at 10+ days after exposure generally believed to be at least 90-95% reliable.  Most likely it's even better, approaching 100% -- but without more research data, it is hard to be certain.

2) This test result doesn't mention p24 antigen, so it is not a 4th generation test -- it appears to be a standalone antibody test (i.e., 3rd generation).  At 18 days, it probably would detect about 70-80% of new HIV infections.

If you have another antibody test at 4 weeks, the combination of that result plus negative RNA at 18 days probably will be virtually 100% reliable.  But for definitive results at that time, a duo (4th gen) test would be preferable; or have another antibody test at 6-8 weeks.

Here are a couple of threads that discuss test reliability at various times after exposure:


Best wishes and stay safe--  HHH, MD
Avatar universal
Thank you for your quick and thorough reply. I will go next wednesday to be tested at the 28 day mark with a 4th generation p24 test.

To clarify its ok to feel a little ok about the Negative "HIV-1 RNA Qualitative" result?

Just need to confirm with this new test correct? Would you recommend subsequent test past the 4 week mark?
239123 tn?1267647614
I think you can take the negative RNA test as highly reliable -- almost certainly you don't have HIV.

Your negative 4th gen test at 4 weeks will be definitive and I would not recommend any further testing.  See the threads linked above for further explanation, if you haven't already looked at them.

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