Welcome to our Rapid Screen Test Laboratories
What is the window period for an HIV

The window period refers to the time between HIV infection and when a test will yield an accurate result for a certain percentage of samples. Different types of tests have varying window periods:

During the window period, an individual can be highly infectious while still testing negative for HIV.

UK guidelines recommend a window period of six weeks for a 4th generation antigen/antibody test (BHIVA/BASHH 2020). By this time, 99% of infections will be detected. Testing after only four weeks will detect 95% of infections.

A negative result at six weeks with a 4th generation test does not require confirmation. However, a negative result from testing earlier—such as after four weeks—should be confirmed with a second test later on.

Time to develop antibodies

The image above illustrates the range of times it can take for individuals to respond to HIV infection.

The earliest marker is the HIV viral load, which can be detected in the first weeks after infection, typically from 1 to 6 weeks post-exposure. A high viral load is often associated with seroconversion symptoms.

The first HIV protein (antigen) that can be measured is p24, detectable from 1 to 8 weeks after exposure. However, viral load and p24 tests are not reliable for diagnosing early HIV if the results are negative.

HIV antibody responses can be detected as early as two weeks in some individuals, with over 99.9% of people showing an antibody response by 12 weeks. An antibody test at 4 weeks can detect 95% of infections.

While antibody testing at 4 weeks can provide a good indication of your HIV status, a test at 12 weeks post-exposure is necessary to confirm that you are HIV negative.

Timeline for HIV infection, immune responses and window period for tests


Both these graphics need to be updated to also show the six week time point.

HIV infection progresses through several stages before it can develop into AIDS (Acquired Immunodeficiency Syndrome). These stages are:

1. Acute HIV Infection

2. Chronic HIV Infection (Clinical Latency Stage)

3. AIDS (Acquired Immunodeficiency Syndrome)

HIV Testing Window Period