The immune response following vaccination with MVA85A is lower in South African than UK adults. Antigen specific IFN-γ ELISPOT responses to Ag85A overlapping peptide pools 0–24 weeks following vaccination with MVA85A are shown. A) MVA85A vaccinated adults (red = South African, blue = UK), n = 22 subjects per time point. *indicates a significant difference in response between UK and South Africa at the indicated time point (Mann Whitney Test *P < 0.05, **P < 0.005). B) The total immune response following vaccination with MVA85A is lower in South Africa when compared to the UK. Area under the curve (AUC) of the IFN-γ ELISPOT response to Ag85A peptides from 0–24 weeks was calculated for each volunteer. AUC values for each volunteer were then plotted by group (red = South African, blue = UK) n = 22 subjects per group. *indicates significant difference from week 0 (Mann Whitney Test P < 0.05).