We found that, after adjusting for potential confounders, countries with ART initiation at CD4 cell counts ≤ 500 cells/μL had an associated 16% reduction in their new HIV infection rates per 100 000, compared with countries with ART initiation at CD4 cell counts ≤ 350 cells/μL (95% CI −30 to −1.4%; P = 0.033). The gene discussed is CD4; the disease is HIV infectious disease.