How accurate is a rapid antibody test at 24 days post exposure? Also, what are the chances of a negative rapid antibody result at 24 days changing at 90 days or 12 weeks assuming no further exposure to HIV.
Hello and thank you for contacting the AIDS Vancouver helpline.
I gather that you are asking about the accuracy and window period of a rapid antibody HIV test.
According to the Canadian AIDS Treatment and Information Exchange: "The window period of the INSTI (rapid) test is estimated to be the same as, or up to one week longer than, the window period for third-generation HIV tests. Third-generation tests can detect HIV infection in 50% of people by 22 days after infection; 95% of people by 40 days after infection; and 99% of people by three months after infection." (1)
Fourth-generation HIV tests and the INSTI rapid test have a sensitivity of about 99.9%. Since the vast majority of people who get tested for HIV are actually HIV negative, the chance of a negative result being false is extremely low.
We recommend retesting at 3 months for a more conclusive result.
Regards, AIDS Vancouver Helpline/Online, Dyson