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Is the fourth generation test after 43 days reliable ?

I assume you are asking about the HIV testing technology called fourth generation testing. The window period is time between potential exposure to infection and the point when the test will give an accurate, conclusive result from an exposure without repeat testing required.

The fourth generation is the “gold standard” and is used across Canada in testing clinics, community settings, and providers offices. A vial of blood is taken, sent to a lab to analyze, then results are sent back to the testing provider (normally within 2 weeks.)

There are factors that can affect a test’s window period that your provider will ask you about during the testing appointment, but the window period for the fourth generation test is usually 1.5 months.  This means that the result is considered conclusive if the blood sample is taken at least 45 days after a possible encounter with HIV. If a fourth-generation screening test indicates that the person who gave the blood sample does not have HIV (also known as a non-reactive test or HIV negative), normally no further testing is performed. If the screening test indicates that the person is infected with HIV (also known as a reactive test or HIV positive), then a confirmatory test is performed to ensure the screening test was correct.

If you are tested 43 days after a potential exposure, you are very close to being outside of the window period. It’s worth asking the testing provider if they think you should come back in for another test, or if what kind of routine testing might be right for you.

(There are a range of HIV technologies available. Because of the differences in these testing options, we often say that the window period for HIV testing in general is 3 months. If you opt for the standard fourth generation blood test, we can usually narrow it down to 1.5 months.) may have more information to make your decision about when to get tested. If you are currently waiting for a testing appointment or for results, we would recommend that you use safer sex and safer drug use practices to prevent exposure to yourself and your loved ones.