We measured plasma human immunodeficiency virus type 1 (HIV-1) RNA levels by means of single-copy assay in 334 participants receiving virologically suppressive antiretroviral therapy (ART). A residual viremia load of ≥1 copy/mL after 4 years of ART was predicted by a higher pre-ART HIV-1 RNA level, higher CD8+ T-cell count during treatment, and a lower ratio of CD4+ T cells to CD8+ T cells during treatment but not by initial ART regimen. In a longitudinal subset of 64 individuals, continued decay of the plasma HIV-1 RNA level was observed, with an average annual decrease of 6% and an estimated half-life of 11.5 years. In contrast to prior reports, the persistent viremia level continues to slowly decline during years 4–12 of suppressive ART.
Clinical Trials Registration: NCT00001137.