[Question #479] Question for the Doctors.

91 months ago
Now rest assured. Dr. Handsfield and Dr. Hook you have assured me 100 percent that I do not have HIV with my 34 day negative duo test. And i thank you again for your kindness and reassurance. That is not what this question is about. I stumbled upon some interesting data on a study that was done about chances of false negatives with tests. Here is the link 


The research is saying that the chances of a false negative result with a 4th gen duo is 0.1 percent at 6 weeks. I'd imagine the number would probably be very very close to that at a 28 day interval would you agree? Maybe like 0.2 percent? Which is basically 0 in all purposes.

Curious as to your interpretation of this data. With a percentile like that in all purposes that would equate to NO chance.

Looking forward to your response.
H. Hunter Handsfield, MD
91 months ago
*Sigh* Bob, Bob, Bob, Bob. One of the worst things anxious people can do is keep searching the internet. Nate Silver is the now famous statistician (fivethirtyeight.com) who, among other things, wrote a book called The Signal and the Noise. Among the things he wrote was (approximate quote): "Put an anxious person in a room with a computer and an internet connection and soon he'll be mistaking his cold for the bubonic plague." In this instance, you've found a nice study that largely confirms the advice I gave last time. Still, all things considered, I think you'll do better to move on without further online investigations!

In my previous reply, I cited the imprecision in the data about HIV test performance, including "So we're left with biological principles, animal studies, and scant data in exposed or newly infected persons." The study cite is very well done, by an excellent and well respected research team. However, the methods in their abstract say this: "Data were extracted from published seroconversion panels." Such seroconversion panels are the sort of thing I was referring to with "scant data in exposed or newly infected persons". These are the best data available in humans, but they are far from perfect. Within the limits of those flawed data sets, the investigators' conclusions appear valid. However, their estimates are more precise only because they combined the imperfect data (using a technique called meta-analysis) from several studies of several available tests.

Having said all that, thank you for drawing my attention to the study. I'm pleased to see that it essentaily confirms the advice Dr. Hook and I have been giving, as I related in your last thread. We agree that for all practical purposes, the chance of a negative duo test at 6 weeks is zero. The only slight difference is that i would confidently shorten that to 4 weeks, with maybe very rare exceptions, e.g. following post-exposure prophylaxis.

Best wishes--  HHH, MD 

91 months ago
Dear Dr. Handsfield.

Thanks for your reply. I did also find that data interesting.

Now, if you were in charge of the CDC guideline policy, Would you change the guidelines regarding HIV testing? I feel there is so much information out there that could make a person crazy (like me)

Literally making people unnecessarily worried about length of time to test for a definitive result. Thinking "i have to stress and worry for 3 months" When you have data backed scientific research that shows otherwise. Is it because some places still only use 3rd gen tests? (Maybe some still use 2nd gen)

However I read the World Health Organization has changed their guidelines to 6 weeks. Which is a good sign. And the BASHH states 4 weeks.

The misinformation out there is widespread. And I totally agree with you that the internet is dangerous for anxious people (like me) 

I wish there were more people out there (experts) such as yourself and Dr. Hook.

Because any general MD will tell you 3 months. Because they are following an outdated guideline.

Were you at all surprised at 4th gen tests when they first came out how accurate they were in such a short time frame?
H. Hunter Handsfield, MD
91 months ago
I wasn't at all surprised by the performence of the 4th gen tests. For experts who understand HIV, those results were expected.

The problem here is one of perspective. Nobody goes out of their way to "mak[e] people unnecessarily worried about length of time to test for a definitive result". OROH, these are not the main concerns of those who design tests or implement widespread HIV testing. That is, the worries of people who test after specific exposures are not the primary concern of CDC and others responsible for public health and clinical services. The large majority of people at risk for HIV, and the main targets of expanded testing, aren't worried (and often are clueless) about particular exposures. People like you, and others who are over-represented on this and similar forums, are the exceptions. For those reasons, I don't expect much change in strategies or official advice from testing agencies any time soon.

That some (many? most?) clinicians still stick with 3 months is a slightly different issue. No agency has gone out of its way to change providers' understandings. Three months is outmoded with modern HIV test methods. OTOH, many clinicians -- like many official agencies -- would prefer to be conservative, i.e. to take no chance of reassuring someone who might actually be infected. The advice from the average doc in practice eventually will catch up, but it will take time.

91 months ago
It all makes sense as to what you are saying. I believe it is universally agreed that the average time to Seroconversion is about 22 days? Correct me if I am wrong on that. I couldn't imagine back in the 80's when first gen tests came out and and practically failed to pick up infections for months. Technology has come a long long way since then.

I really hope there will be an HIV vaccine/cure one day. Mind you with HAART therapy a person diagnosed early can live a normal lifespan. 

Have you heard of that man who claimed he had a cure by injecting the HIV Virus into goats and than taking the goat serum antibodies and injecting them into HIV patients and their viral loads became undetectable and essentially never returned.

Could be quackery but it seemed interesting.

Also wanted to let you know I had a 41 day 6 week duo test negative again. These tests are purely for psychological support.

Once again. Take care sir.
H. Hunter Handsfield, MD
91 months ago
Thanks for the thanks. I can't vouch for "unversal agreement" about the average seroconversion time. I will point out that "seroconversion" is normally used to refer strictly to antibody testing, not to antigen testing and hence not necessarily to duo tests. I would have thought the "average" time for duo test positivity would be shorter than 22 days. And even there, which "average" is intended? Mean or median? Statistically, it can be a big difference.

I am unfamiliar with and very doubtful of the HIV cure you report.

Of course no surprise your latest test was also negative. It will stay that way forever, assuming no new exposure.

That concludes the two follow-up comments and replies that come with each new question, so this thread will be closed. Please resist any itemptation to post any more questions related this exposure and related issues. Thanks.