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I am a heterosexual female and my last exposure was unprotected vaginal intercourse with a male of  unknown status on November 27th, 2014. I am from Ontario, Canada and i know that labs here use either the 3rd generation or the 4th generation combo test. I have no information on what type my doctor used. Anyways, i tested negative at 6 weeks and negative again at 8 weeks. I know 12 months is conclusive but is it likely for my 8 week negative result to change to a positive? I can't seem to get this out of my head.

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Avatar universal
Your result will not change. It was most likely a combo test since that is the standard test given in Canada (I live in Canada) All blood tests in Canada are 4th gen and only rapid tests are 3rd gen. I confirmed this with an HIV clinic. Remote areas might not use the 4th gen but in Ontario I would definitely say it was a 4th gen. Your results are conclusive. 12 months is only if you are using antibody only testing. I highly suspect you had a duo/combo test.
Hi, sorry for asking questions again but i just had a question. So i tested at 6 weeks DUO (negative), 8 weeks DUO (negative), 10 weeks rapid fingerpick INSTI test (negative) and 11.2 week rapid fingerprick INSTI test (negative). Are my results conclusive?
Avatar universal
I just confirmed with CATIE (Canadian Aids Treatment Information Exchange) that virtually all labs in Canada are using the 4th gen test
Thank you so much for your information!
Avatar universal
A negative result at 8 weeks is extremely unlikely to change. Almost all doctors have said they've never seen it happen. But, some people including me, always go for the 12 week post exposure mark.
I would advise you to test at 12 weeks post exposure and expect a very negative result.
Thank you!
Avatar universal
Does anyone know why in the UK the BASSH guidelines consider a 4 week DUO test accurate and 8 weeks conclusive yet in Canada, they only consider 12 weeks accurate for HIV testing - even with the DUO. I'm just curious because if its the same test, wouldn't the window period be the same?
Avatar universal
Because most public health agencies in Canada use out dated guidelines and don't realize with modern HIV testing (4th Generation) waiting 12 weeks for a conclusive result is completely unnecessary and creates needless anxiety and worry. It also depends where you go. I've called up a few clinics and some have said 4 weeks is conclusive with the Duo test. Called another clinic and they said nothing is conclusive for 6 months. Go figure. I do expect the guidelines to change especially regarding 4th gen testing.

I go by what experts say. As well as the CDC who finally updated their guideline back in 2014 regarding DUO testing.

4 weeks or anytime after with a duo is conclusive.
Avatar universal
They are the exacy same tests with the same window period.
Avatar universal
It is also mind boggling because the DUO test is the standard test across Canada. Again it really depends who you ask because everyone will give you a different answer (which health clinic you go to, which doctor you speak with)
Avatar universal

Reason 1:

Kindly check the following links and their DATES. They both include comments of Dr Sean and Dr Jose.


In 2008, both doctors talk about the merits of the DUO test at four weeks, with Doctor Sean taking a slightly more conservative stance.

In 2014, and with 8 years more experience, you see Dr Sean still going for the 12 week mark saying:

"The standard guidance is that people should test 12 weeks after finishing PEP or 16 weeks after the original exposure.



Furthermore, you see doctor Jose in 2011 also going for three months and quoting UK guidelines despite not having seen any cases turn negative after 8 weeks.

"However current UK guidelines still recommend to have a final test at 12 weeks for it to be considered final and fully conclusive"


The doctors know when to say conclusive or inconclusive based on their OWN assessments.

Reason 2

Please bear in mind that at 4 weeks an antibody test is NOT conclusive, and that is exactly what the DUO at 4 weeks is for HIV-2.
It detects antibodies and antigen for HIV-1, but only relies on the detection of antibodies for HIV-2. ((HIV-2 is VERY rare, but unfortunately very real)).

An antibody test at 12 weeks would CERTAINLY detect antibodies for both types.


Reason 3:

Please take a look at link below.


People from ALL OVER THE WORLD post questions on this forum. Sometimes with high command of English and sometimes with lower.

Sometimes the word "DUO" or "4th gen" may be lost in translation, but the term "12 weeks" is more likely to stick. So, a person with low English proficiency may remember the "4 weeks" from the sentence "Get a DUO test at 4 weeks", but may not comprehend, remember the name of the test or may even fail to communicate it to the lab in there own language.


Only test manufacturers can set actual guidelines for testing. The CDC makes recommendations, and the doctors in the filed can interpret them.

I am not a doctor, nor is anyone in this thread. That is why I said it is a personal decision when to test, and a person can take all of this information and make their choice.

No one in this thread is actually wrong, so have a great day, everyone. This thread is now closed.




Put all the above together and it may make sense why some members ((here)), including me, may advise testing at 12 weeks.

Avatar universal
Yes. Stop testing.
Avatar universal
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