In two recent Phase I/II trials of the CS-based RTS,S vaccine, immunized malaria-naïve volunteers who developed sterile immunity following P. falciparum sporozoite challenge had significantly higher concentrations of anti-repeat antibody (114–188 μg/ml) and multifunctional CD4 + T cells when compared to non-protected individuals (30–73 μg/ml) (Kester et al., 2008, 2009). Here, CD4 is linked to malaria.