False positive test result for HIV infection: causes

A false positive result is a test result that shows that a person has HIV infection in his or her body when in fact there is not. An ideal HIV test would correctly identify all HIV-positive and HIV-negative people 100% of the time. However, although most HIV tests are extremely accurate, they are not 100% accurate.

Causes of a false positive HIV test result

Tests for HIV infection work on the principle of detecting antibodies to the immunodeficiency virus in the human body. Antibodies are proteins produced by the immune system in response to a foreign virus such as HIV.

The main reason for false positive results is that the test detects these same antibodies, but they are not antibodies to HIV infection. The antibodies detected by an HIV test may actually be produced to another virus or infection, and although HIV tests should not react to other types of antibodies, sometimes they do.

There are other reasons why an HIV test may give a false positive result. Depending on the type of analysis, interpretation of its results may be based on subjective interpretation. When the test result is borderline, experienced doctors give more accurate results.

A false positive result may also be the result of a sample being mislabeled, mixed with another person's sample, or some other technical error.

Less commonly, false-positive HIV test results may occur in people who have recently received a flu vaccine or have an autoimmune disease such as lupus.

Reactive HIV test result and follow-up testing

The result of an HIV test alone cannot serve as the basis for a definitive HIV-positive diagnosis.

Because of the possibility that a positive result from a single HIV test may be a false positive, most doctors prefer to call the result "reactive" rather than "positive." If the result is reactive, it indicates that the test has reacted to something in your blood and needs further investigation.

That is why the preliminary result of an HIV test must be confirmed or refuted by a series of confirmatory tests.

If your initial testing was done using a home rapid HIV test, it is recommended that you repeat this procedure again using a new rapid test. If the HIV test was carried out in a medical setting, the laboratory will conduct several tests on the blood sample if the test result is positive before telling you the result.

Only after you have been tested for HIV, followed by a series of confirmatory tests, and a positive result has been confirmed, can you be sure that you are infected with HIV and begin immediate treatment.