I just underwent screening for STDs including HIV and was startled to see that my HIV Ab/p24 Ag with Reflex screen came back "Preliminary Reactive." Other HIV tests were negative, though: the HIV 1/2 Ab Differentiation test came back "Non Reactive" and the HIV-1/HIV-2 Qualitative RNA test also came back "Non Reactive". 

Under the HIV-1/HIV-2 Qualitative RNA section, it had a "Final Interpretation" that read: "HIV antibodies were NOT confirmed and HIV-1 and HIV-2 RNA was NOT detected. No laboratory evidence of HIV Infection. Possible biologic false positive." My impulse is to interpret the ""Preliminary Reactive" screen as a false positive and to trust my "Non Reactive" confirmatory tests, but want to be sure that is the right thing to do. What is the right way to interpret these results? What are the appropriate next steps? How concerned should I be?

"What is the right way to interpret these results?" Of course I understand that the test report was a bit alarming. But it is 100% certain you do not have HIV. False positive results on HIV screening tests are rare, but are well known. The follow-up confirmatory testing is completely reliable. And you not only have no detectable HIV p24 antigen or antibody, but also no HIV RNA in your blood. You're good and no additional testing is necessary. "What are the appropriate next steps?" Nothing. "How concerned should I be?" Not at all.

FYI, the cause(s) of preiminary false positive test results are unknown. I doubt your flu shot has anything to do with it. Future HIV AgAb tests you may have probably won't have the same outcome, although you should be prepared for the possibility.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD

I know you get it all the time, but I very much appreciate the reasonable, expert advice that you provide here. With all the misinformation out there, this site is an amazing service to the community.