In the past, clinicians often hoped to achieve a target viral load reduction, measured in ‘logs.’ But with the more effective therapies available today, experts now recommend that the goal for all patients - regardless of treatment history - should be to bring viral load to an undetectable level.

The current standard viral load test has a ‘limit of detection’ of 50 HIV RNA copies/ml. An earlier version of the test could only measure viral load down to 400 copies/ml. Older studies, therefore, often reported treatment effectiveness in terms of viral load below 400 copies/ml.

According to the 2006 British HIV Association (BHIVA) HIV treatment guidelines, the aim of anti-HIV therapy should be to suppress viral load below 50 copies/ml within 24 weeks of beginning treatment, particularly when starting antiretroviral therapy for the first time.^[1]

For people who have never taken anti-HIV drugs before, there is now a very good chance of suppressing HIV below 50 copies/ml with their first regimen.^[2] Studies show that with modern potent first-line regimens, approximately 70% of people starting combination treatment in ‘real world’ settings can achieve a viral load below 50 copies/ml, and rates as high as 80% to 90% have been seen in some clinical trials.^[3]

Among treatment-experienced people who have previously taken anti-HIV drugs, approximately 60% can be expected to achieve a viral load below 50 copies/ml using the newest protease inhibitors.^[4]