Antiretrovirals—the drugs used to keep HIV in check—don’t only prevent people from getting AIDS; they also keep virus levels low, making those taking them less likely to pass the infection to others.

This phenomenon has opened a new avenue for the fight against HIV: Treatment as Prevention.

Since 2015 the World Health Organization has been urging countries to offer ARTs immediately to people who test positive, instead of waiting for their immune systems to deteriorate beyond a set point. In this ‘test and treat’ scenario, the theory goes, more people will have suppressed viral loads, which means there will be less transmission, ultimately leading to less HIV all round. ….more