This is not a question,
I am sharing information from officials and not opinions even from specialized Drs.
The Window defer from test to test From 4 weeks to Maximum 12 weeks depend on the test taken
Lets start in the most conservative which is CDC in USA:
What does a negative test result mean?
A negative result does not necessarily mean that you don't have HIV. That's because of the window period—the period after you may have been exposed to HIV but before a test can detect it. The window period depends on the kind of test that was used on your blood or oral fluid. For antibody tests, if you get a negative result within 3 months of your most recent possible exposure, you need to get tested again at the 3-month mark. For RNA tests or antibody/antigen tests, that timeframe may be shorter. Ask your health care provider if and when you need to be retested with a negative test result. And meanwhile, practice abstinence or mutual monogamy with a trusted partner, use condoms every time you have sex (and for every sex act—anal, oral, or vaginal), and don't share needles and other drug equipment (works).
http://www.cdc.gov/hiv/basics/testing.html
From the a above, (you need to get tested again at the 3-month mark) which means the maximum window for the Antibody test is three months and it is less when it comes to the combo (4th generation)
from their new release chart, it is 3-4 weeks earlier see link
http://www.cdc.gov/nchhstp/newsroom/2014/HIV-Testing-in-Laboratories-graphics.html
Going to UK which has been using the 4th generation test before the US and based on their data and the Department of health announcement based on BASHH recommendation:
"A negative result on a fourth generation test performed at 4 weeks post-exposure is highly likely to exclude HIV infection. A further test at 8 weeks post-exposure need only be considered following an event assessed as carrying a high risk of infection."
So from the above it is clear that 4 weeks is sufficient however 8 weeks is reassurance for high risk.
and in their previous statement on 2010 they have mentioned that by 12 weeks it is definitive.
https://www.google.com.sa/search?rlz=1C1GGGE_enSA525SA596&espv=2&q=bashh+hiv+test+window+2010&oq=bashh+hiv+test+window+2010&gs_l=serp.3..33i21.2470.3035.0.3180.5.5.0.0.0.0.150.150.0j1.1.0.msedr...0...1c.1.62.serp..4.1.149.p1gn-aVJcK8
In Eroupe:
Interpreting negative HIV test results. Individuals whose specimens test negative on the initial HIV screening should be considered non infected unless the patient presents with symptoms of primary HIV infection or has a history of recent (6 weeks for fourth generation assays, 12 weeks for other assays) high-risk exposure (IV, C)
. In the case of recent exposure, the tests should be repeated at 6 weeks to 12 weeks (according to the test to be
used) from the time of exposure31,36,42 (IIb, B).
. Individuals with a high-risk exposure to HIV should
not be fully reassured until the test process is completed43 (IV, C).
. When using fourth generation assays, individuals who have a negative screening test after 6 weeks of
exposure may be recalled for a follow-up in specific circumstances, e.g. if post-exposure prophylaxis
(PEP) was given for any reason (e.g. occupational or sexual exposure), with patients who are very
anxious and seek further reassurance, where there is impaired ability to develop antibodies and where
there is microbiologically proven simultaneous acute infection with another viral pathogen, such as
human cytomegalovirus or hepatitis C virus.2,44–46 n this case, the final testing time may be 12 weeks
after exposure (IV, C).
So, For thr 4th generation window, it is 6 weeks.
http://www.iusti.org/regions/europe/pdf/2014/2014IUSTIguidelineonHIVtesting.pdf
the link was taken from :
http://www.iusti.org/regions/europe/euroguidelines.htm
BC Centre for Disease Control, June 2010
"Earlier testing can help if clients are anxious about their HIV status following a potential
exposure to HIV. An early negative result at 6 weeks, which is likely to remain HIV negative at
three months, may help to reduce anxiety"
http://www.bccdc.ca/NR/rdonlyres/2982E293-BD82-436D-B193-F929B5CEEBEC/0/HIVTestinginBCResourceDocumentforHealthProfessionalsJune2010.pdf
Going to WHO (World Health Organization)
Diagnosis
An HIV test reveals infection status by detecting the presence or absence of antibodies to HIV in the blood. Antibodies are produced by an individual’s immune system to fight off foreign pathogens. Most people have a "window period", usually 3 to 6 weeks, during which antibodies to HIV are still being produced and are not yet detectable.
This early period of infection represents the time of greatest infectivity, but transmission can occur during all stages of the infection. If someone has had a recent possible HIV exposure, retesting should be done after 6 weeks to confirm test results, which enables sufficient time to pass for antibody production in infected individuals.
http://www.who.int/mediacentre/factsheets/fs360/en/
In Melbourne Sexual Health Centre, Australia
WHAT DOES A NEGATIVE HIV ANTIBODY TEST RESULT
MEAN?
It means either
• That a person has not been infected with HIV
Or
• That a person has been infected with HIV recently
(within the last 6 weeks), but has not yet produced
antibodies. Remember it can take up to 6 weeks
for antibodies to develop after the initial infection
with HIV; this is called the window period. Please
note that there are some circumstances where
the window period is up to 12 weeks.
http://www.mshc.org.au/portals/_default/uploads/fact_sheets/hiv_antibody_test_ext_a4.pdf
In Canada:
NEGATIVE
If baseline testing is done while the client is in the window period, retest at three weeks and
three months after most recent at-risk behaviour; counsel client to maintain risk reduction
practices until all testing is complete. If no risk behaviour was present in the three months
prior to the first test, a negative result is conclusive.
http://www.catie.ca/sites/default/files/EN_HIV-Screening-Guide-2013.pdf
New York:
http://www.hivguidelines.org/clinical-education/hiv-qa-fact-sheets/window-period-for-hiv-infection/
AIDS Foundation of South Africa:
http://www.aids.org.za/testing-and-treatment/
Finaly:
How long after taking a risk can I be sure that
I am HIV-negative?
To be certain, BASHH recommends re-testing three
months after the last possible exposure to HIV.
Although the majority of infections are detected
within a month, and almost all within six weeks, there
are occasional cases when it takes longer. This period
will be longer if someone has taken post-exposure
prophylaxis (PEP).
http://makingitcount.org.uk/files/MiC-briefing-10-TestingTechnologies.pdf