Hi Bob86, On this occasion, I suggested that they retest as they did not feel confident in their result. Although they did not need to retest, after receiving a negative result post-exposure, two negative results are more reliable than just the one and therefore it may help to ease their worries. All the best, Becky

Hi Igo97, false-negative results occur most often when users test inside of the window period as the test cannot accurately detect infection if no antibodies have yet been produced. False negatives are much less common outside of the window period. Hope this helps. Kindest regards, Becky

Hi there, Just out of curiosity was wondering why the advice here is to retest? Usually the message is that if the test has been taken 12 weeks post exposure then its conclusive and there is no need to retest. Thanks

What can cause false negetive because it was outside the window period?

Hi IGO97, The onset of symptoms is known as seroconversion; usually occurring 1-4 weeks after infection. During this period HIV infected individuals experience flu-like symptoms as their bodies create antibodies in response to the infection. After the seroconversion period, HIV is asymptomatic and the individual will show no signs of infection (unless they test). Given that you tested at 22 weeks and received a negative result suggests that your body will have produced antibodies to the infection by now and your result is reliable. However, if you are really worried that your symptoms are related to HIV and that your test result may have been false, you should retest in another 3 weeks. Kindest regards, Becky