HIV immunological window: what it is and when to get tested

The immunological window is the period between exposure to the HIV virus and the production of antibodies against this infection by the body, in sufficient quantities to be detected in a test.

Generally, the immunological window for HIV is 30 days, but this time can vary depending on the body’s reaction to the infection and the type of test used. Therefore, in cases of suspected HIV infection, where the tests give a false negative result, it may be recommended to repeat the test.

Read too: HIV test: what it is, when to do it and how to understand the result

During the immunological window period, the HIV virus can already be transmitted. Therefore, during tests or blood donations, it is important to always inform about risk behaviors, such as sharing needles, unprotected sexual intercourse or piercing with contaminated cutting objects such as knives or scissors.

When to get tested for HIV

The period for taking an HIV test varies depending on the type of test used, including:

• Rapid Antibody Test: Done with a blood sample taken from a fingertip, this test can detect HIV between 18 and 90 days after exposure to the virus. See how the rapid HIV test is performed;
• 4th generation antigen/antibody ELISA test: It is done with a blood sample to be evaluated in the laboratory, and can detect HIV between 18 and 45 days after exposure to the virus;
• Nucleic acid test (NAT) or molecular examination: Done in a laboratory with a blood sample, it detects HIV approximately 10 to 33 days after exposure to the virus.

Generally, the immunological window for HIV is 30 days, but this time can vary depending on the person’s body’s reaction to the infection and the type of test used.

Therefore, people who have engaged in risky behavior and have taken the test but received a negative result must repeat the test after 30 to 60 days to verify the presence or absence of the virus.

A false negative result is one that occurs when the test is carried out during the immunological window, that is, within 30 days after the risk behavior. This happens because, during this period, the body is still unable to produce sufficient quantities of antibodies to be identified in the test.

However, even if the test was carried out 30 days after the risk behavior, the body can take up to 3 months to produce sufficient antibodies against the HIV virus and the test result is positive.

Therefore, it is important that the test is repeated 90 and 120 days after the risk behavior to confirm the presence or absence of the HIV virus in the body.

Difference between immunological window and incubation period

The incubation period corresponds to the time between the moment of infection and the appearance of the first symptoms, varying according to the type of infection.

On the other hand, the immunological window is the time it takes the body to produce antibodies specific to the type of infection. Thus, in the case of the HIV virus, for example, the immunological window is generally 30 days, but the incubation period varies between 2 and 6 weeks.

Despite this, a person with the HIV virus can live for years without showing symptoms of this infection. Therefore, it is important that the infection is monitored periodically and tests are carried out after risk behavior, according to the immunological window.

Read too: First symptoms of HIV and AIDS (and each stage of infection)