Figure 1

Hemagglutination inhibition antibody responses before (day 1) and after (day 22) influenza vaccination, and cellular proliferation before (day 1) and after (day 8) influenza vaccination. Both immune responses are presented for the three influenza strains of the vaccine (H3N2, H1N1, and B), in chronic fatigue syndrome patients (A and C) and healthy controls (B and D). Antibody titers are presented as mean ± standard error of the mean, the dotted line indicates the protective titer cut-off value. Proliferation counts are presented as absolute numbers and mean (horizontal line) on a logarithmic scale.