Fig 3. Antibody responses to the vaccine strains by age and group, as determined by HAI.

The antibody responses for the 4 mg DNA-IIV3 and the IIV3-IIV3 regimens are displayed as group means based on the (A) magnitude of response at 4 weeks post boost, (B) geometric mean fold increase of titers from baseline at both 4 and 24 weeks post boost, and (C) seroconversion rates at 4 weeks post boost. DNA-IIV3 values shown in black, and IIV3-IIV3 in grey. Comparisons were made between the DNA-IIV3 and IIV3-IIV3 groups using Fisher’s exact test for serconversion rates, and t-test for response magnitude using log-transformed HAI titers.