Approach to HIV Screening

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Organization: Public Health Agency of Canada

Date published: December 2020

Types of HIV Screening Tests

The choice of HIV test may vary depending on clinical evaluation and the person’s history, including length of time since potential exposure and access to specialized personnel (phlebotomy).

Standard HIV Testing

All laboratories performing HIV screening in Canada use fourth-generation (combination) HIV tests, which detect both HIV antibodies and the HIV p24 antigen. These tests perform better in acute infection than tests that only detect antibodies because the p24 antigen appears earlier. Some people with HIV infection will have a reactive (positive) result as early as 15 to 20 days after HIV exposure; by 35 days, as many as 95% will have a reactive result. Note that the window period can be up to 12 weeks. If an HIV screening test indicates a reactive test result, the laboratory will conduct specialized confirmatory testing to ensure correct diagnosis of an HIV infection.

Rapid HIV Testing (Point of care and self-testing)

Rapid HIV test kits licensed in Canada for point-of-care (POC) testing or self-testing require a few drops of blood from a finger prick and provide results within several minutes. Because rapid tests only detect HIV antibodies (third generation), they generally have a longer window period than standard HIV tests (fourth generation). While some people may have a reactive result as early as 20 to 30 days after HIV exposure, the window period can be up to 12 weeks. Reactive results are considered “preliminary” and should be confirmed with standard laboratory testing.  

Window period: In most individuals, antibodies can be detected within weeks of HIV exposure.

If the HIV test is non-reactive (negative) and a potential exposure occurred less than 12 weeks prior (i.e., during the window period), repeat HIV testing should be offered.

For more information, consult with local public health laboratory or provincial/territorial guidelines.

Check with local public health unit about the availability of POC testing.

Barriers and Facilitators of HIV Screening

How Healthcare Providers Can Facilitate HIV Screening

Healthcare providers should take an active approach to HIV screening, as earlier diagnosis and treatment leads to better health outcomes. Individuals with positive results should be linked to treatment and care. Those with negative results may benefit from counselling on risk reduction and prevention measures.

Healthcare providers are encouraged to decrease barriers to HIV testing. These barriers may include:

To facilitate HIV testing, healthcare providers can:

HIV self-testing and POC testing (where available) can facilitate uptake of screening. In addition, HIV self-testing provides an option for people who face barriers to accessing testing in healthcare settings.

Offering an HIV Test

In Canada, HIV testing is voluntary: the person is free to accept or refuse testing. When offering an HIV test, healthcare providers should ensure the individual understands:

Note: Verbal consent is sufficient to proceed with testing.

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