What is viral suppression? When HIV infection is untreated, viral load is very high. Starting antiretroviral treatment stops HIV from multiplying, suppressing viral load. Over time, viral load drops so low that it is undetectable, although HIV still hides in viral reservoirs. When a person stays on treatment and maintains an undetectable viral load for at least six months, they are considered to have a durably undetectable viral load. When you have a durably undetectable viral load, there is effectively no risk of transmitting HIV to your sexual partner.