Immunogenicity of DNA C plus NYVAC C versus NYVAC C–alone vaccine regimens. (A) Percentage of responders in the two study groups at weeks 26/28, i.e., primary endpoints of the study. The percentage of responders was calculated on the basis of volunteers with a positive IFN-γ ELISPOT assay at weeks 26/28. (B) Percentage of responders at the different time points across the duration of the study.