The amount of a particular virus present in a person’s body, usually measured by detecting viral genetic material in a sample of blood or another body fluid.
In HIV infection, viral load usually refers to the amount of HIV RNA in the blood, reported as copies per milliliter. It is an important measure of how actively HIV is replicating and how well antiretroviral therapy is controlling the infection.
Effective ART can reduce HIV viral load to levels that laboratory tests cannot detect. An undetectable viral load does not mean HIV has been eliminated from the body; it means the amount of detectable virus is below the test’s detection threshold. Sustained viral suppression prevents sexual transmission of HIV (U=U Undetectable = Untransmittable).
QUICK FACT
An undetectable viral load does not mean “no HIV.” HIV remains in the body, which is why ART must generally be continued.
COMMONLY CONFUSED WITH
CD4 count: Viral load measures the amount of HIV in the blood, while CD4 count measures the number of CD4 T lymphocytes in the blood. Together, they provide different information about HIV infection and immune health.
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