HIV rapid testing

Fourth generation HIV immunoassays and NATs have enabled identification of people with PHI prior to the development of HIV-specific antibodies, however these methods entail blood collection and laboratory testing and may be inconvenient for the person being tested. Point-of-Care (POC) or rapid tests, first introduced into Australia in 2018, are screening tests performed independent of the laboratory. These tests may utilise saliva or finger-prick capillary blood and provide results within 10-20 minutes through visual interpretation. These tests have clear benefits in resource-limited settings in the absence of formal laboratory support. They also have utility in developed countries, making testing more accessible and applicable to the significant minority of individuals tested for HIV who never return to receive their test results. Such individuals represent a significant public health risk, particularly in the highly infectious period of PHI39, 40.

Although the rapid tests available in Australia are required to demonstrate a high level of sensitivity and specificity prior to approval for use, it is important to be aware of their limitations, particularly in the setting of PHI, where the window period of rapid tests may be prolonged compared with formal laboratory testing. It was demonstrated that if POC testing alone was to be performed in high-risk individuals in Australia, there is a potential for failing to detect a significant proportion of PHI at the earliest opportunity41. Careful consideration of their use should therefore be undertaken when patients present with symptoms suggestive of PHI.  It is a requirement that all reactive POC tests should be confirmed by conventional diagnostic laboratory tests, including those conducted in community-based and outreach testing settings.

Nevertheless, there has been a recent recommendation by the WHO toward replacing laboratory-based HIV diagnosis (especially via western blotting immunoassays) with simpler POC testing, especially in developing countries. This is based on a body of evidence suggesting that the performance of POC tests is comparable to that of laboratory-based tests and that their use enables both positive and negative determinations to be made much more quickly42. This allows management to be instituted more rapidly, with consequent public health benefit.