A National Institutes of Health study has confirmed that taking antiretroviral 
drugs and maintaining an undetectable viral load reduces a positive person's  risk of transmitting the virus to HIV-negative sexual partners by 96 percent among heterosexual couples. Called HPTN 052, the study makes a strong case for treatment as prevention. Given that only 6 million of the 33.3 million people living with HIV globally can access ARVs, it remains  a theoretical solution.