Giant prevention study has sobering message

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Science  15 Mar 2019:
Vol. 363, Issue 6432, pp. 1132
DOI: 10.1126/science.363.6432.1132

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The largest HIV prevention study ever held yielded mixed results and underscored how difficult it is to end AIDS epidemics. The study, called Population Effects of Antiretroviral Therapy to Reduce HIV Transmission, involved 1 million people in South Africa and Zambia. It aimed to assess the power on a community level of testing and treating all infected people, which is known to both stave off disease and make people less infectious. Community health workers for 3 years went door to door and tested two-thirds of the people for HIV, and either linked infected people to care immediately (arm A) or, based on country guidelines (arm B), when they'd suffered some immune damage. A control group (arm C) did not receive services from the study. The communities in arm B had a 30% reduction in a new infections compared with arm C, but much to the surprise of the researchers, arm A—which should have had the biggest drop in incidence—only had an insignificant 7% decline. This is the fourth large-scale study to examine testing and treating large swaths of a population. Altogether, they have cost more than $200 million, and none has reported a clear answer to a central question in the push to end AIDS epidemics: What percentage of people must know their status and receive effective treatment to drive down new infection rates to the point at which spread peters out?