To characterize viro-immunological outcomes following long-term combined antiretroviral therapy (cART) initiated during primary HIV infection (PHI) or chronic HIV infection (CHI) and to identify factors predictive of optimal viro-immunological responder (OVIR) status.

This was a prospective, single-centre cohort study of HIV-1-infected patients on effective cART. Total cell-associated HIV DNA levels and T cell counts before and during treatment were used to identify factors predictive of OVIR status {i.e. low HIV DNA level [<2.3 log₁₀ copies/10⁶ peripheral blood mononuclear cells (PBMCs)], together with normalization of the absolute/relative CD4+ T cell counts and CD4+/CD8+ ratio}.

A total of 307 patients were enrolled, of whom 35 started cART during PHI (<4 months post-infection) and 272 during CHI. HIV DNA decay was modelled with a non-linear mixed-effects model that showed two phases of HIV DNA decay, both of which were significantly more pronounced in the PHI group. At the end of follow-up, after a median of 4 years of viral suppression (<50 copies/mL), HIV DNA levels were lower in the PHI group than in the CHI group (median = 2.15 versus 2.84 log₁₀ copies/10⁶ PBMCs; P< 0.0001). Immune reconstitution was more rapid and sustained in the PHI group (median = 883 versus 619 CD4+ cells/mm³; 41% versus 31% CD4+; CD4+/CD8+ 1.31 versus 0.77; all P< 0.0001). Finally, OVIR status was obtained in 19/35 (54%) and 7/272 (3%) patients in the PHI and CHI groups (P< 0.0001), respectively. In a logistic regression analysis, cART initiation during PHI (OR = 16, 95% CI = 3.5–72.3) and HIV DNA level <3.3 log₁₀ before treatment (OR = 4.8, 95% CI = 1.2–19.3) were independently predictive of OVIR status.

Initiating cART during PHI represents a major opportunity to reduce HIV reservoirs and achieve optimal immune reconstitution.