HIV self-tests (home tests) frequently give false-negative results when used by people with diagnosed HIV who are taking antiretroviral therapy, with implications for the messaging around self-testing, according to a South African study presented at the 10th International AIDS Society Conference on HIV Science (IAS 2019) in Mexico City yesterday.

Testing programmes report significant numbers of people who have already been diagnosed re-testing, sometimes as part of a process of re-engaging with care but often because of doubts about the initial diagnosis. In the South African context, there are significant numbers of bogus practitioners who claim to cure individuals. With increasing discussion of ‘undetectable = untransmittable’, an emerging reason is due to misunderstanding of the nature of an undetectable viral load.

“’Undetectable’ doesn’t mean that you have reverse-seroconverted,” commented Dr Mohammed Majam of the Wits Reproductive Health and HIV Research Institute, who presented the study. As self-testing programmes scale up, there are more opportunities for people to test, but without any interaction with healthcare professionals who might be able to explain the meaning of a result or arrange follow-up testing. Self-testing is attractive to many people precisely because of its confidentiality.

The danger is that people who want to reconfirm their status get an indeterminate or non-reactive result (i.e. a false negative) or low-reactive (indeterminate) result and stop taking their antiretroviral therapy.