4 weeks or 12-13 weeks HIV testing?

[meworriedme]

Dears,
I am confused.
On one hand many HIV specialists confidently claim that a combo Ag/Ab negative test after four weeks is conclusive and here's one convincing example:
http://www.medhelp.org/posts/HIV---Prevention/Hard-time-moving-onCOMBO-test-at-6-Weeks/show/1843858
On the other hand, there is much advice on this forum too that a test after 12 weeks is conclusive.
Maybe it's a matter of interpretation, esp. of the second statement. Why talk about 12 weeks at all instead of for example minimum 4 weeks (condemning many stressed ppl to max 12-4=8 weeks more waiting) in case of 4th generation tests (eg. HIV Ag/Ab Combo)?
Is it because WHO recommendation is still based on 3rd generaton tests?
Please do explain.
Thank you,
MeWorriedMe

[Teak]

There are no tests marketed or sold to give a conclusive negative test earlier than 3 months post exposure.

[meworriedme]

Thank you but the reason you give: "because 97% of people turn positive if they are infected.." Then my question was in other words: is the percentage of positive results any lower after 6 weeks in case of 4th generation tests? Have cases of negative turning to positive between 6 and 12 weeks been registered? Would you really consider 97% conclusive?
I have hard time believing that Experts on this forum irresponsibly mislead patients by pretending that past 6 weeks result is conclusive. I'd rather tend to interpret that the contents quoted by Teak (thank you!) have gone a long way to certification and are probably based on 3rd generation testings rather than 4th whereas the experts share their first-hand scientific knowledge which normally sources the national or international guidelines byt has not yet gotten through this institutionalized formalized multi-stage decision-taking machine...

[Andyjohn]

Teak is absolutely right 4 weeks can be a good indicator but cannot be conclusive. Retest after 3 months for conclusive results because 97% of people turn positive if they are infected..

[Teak]

There are no tests marketed or sold to give a conclusive negative test earlier than 3 months post exposure.

[meworriedme]

Thank you. As far as I understand, the two sources kind of contradict each other:

"1.  The results of combination HIV p24 antigen/HIV antibody tests provide definite results at 4 weeks.,  If your tests are negative at this time, you should believe them."

Edward W Hook, MD

Or is my understanding wrong?

[Teak]

http://www.cdc.gov/globalaids/Resources/pmtct-care/docs/TM/Module_6TM.pdf
Page 11
#4
  In an adult, a positive HIV antibody test result means that the person is infected, a person with a negative or inconclusive result may be in the “window for 4 to 6 weeks but occasionally up to 3 months after HIV exposure. Persons at high risk who initially test negative should be retested 3 months after exposure to confirm results

[meworriedme]

Yes and I tested negative (HIV Ag/Ab Combo) after 6 weeks, hence my question but I believe a pertinent answer could benefit big deal of the forum community where post-exposure "28 days" are pretty much mixed with "12 weeks" meaning the earliest conclusive testing time.
Thank you.

[Teak]

Did you have a possible exposure?