A test of PrEP on 2,400 drug addicts in Thailand, where shared needles are a hugely common way to transmit HIV. Participants were given a PrEP daily. Then they were tested for transmission. The participants who were taking PrEP were 74%  less likely to be infected. Researchers know that PrEP works for an at-risk population. However,  it is going to be hard to get addicts to commit to the treatment. It’s sad to think but one researcher even said that “the cost of distributing PrEP meds might actually outweigh the benefits, along with overshadowing proven outreach programs like clean needles, methadone, and test-and-treat.”