A test result that incorrectly indicates that the condition being tested for is not present when, in fact, the condition is actually present. For example, a false negative HIV test indicates a person does not have HIV when, in fact, the person is infected with HIV. False negative non-reactive tests are not common in standard HIV clinical testing. In some rapid tests if you have taken the test too close to when the infection has occurred that test result might not show up HIV-antibodies as your body hasn’t had time to develop them. It can take up to 30 days before your immune system has reacted to the presence of HIV and therefore developed antibodies. This is called ‘the window period’. Other tests can be run if a test is suspected to be false-negative (for example the p24 antigen test).