CD4 and infection: A decrease in SIV-DNA copies in vaginal mucosa was more pronounced in young vaccinated animals (p = 0.045; medians for the vaccinated and control groups = 305 and 8384, respectively; Fig. 1f) than old (p = 0.067; medians for the vaccinated and control groups = 306 and 4343, respectively; Fig. 1g), with transient protection from CD4+ T-cell loss occurring in young animals at week 2 (p = 0.012), and in old animals at week 10 post-infection (p = 0.027; Supplementary Fig. S1b, c) when compared to aged-matched infected controls.