FIG 3 .

Reported seasonal influenza virus vaccination is associated with enriched HA-specific antibody titers. Endpoint ELISA titers were determined for avian H4, H5, H6, H8, and H12 and human H7 hemagglutinin antigens. Seasonal vaccination status indicates whether participants had reported receipt of any seasonal (pre-2009) influenza vaccination or the H1N1pdm09 influenza vaccine. Whiskers of box plots represent 10th and 90th percentiles, and the horizontal line and plus sign in each box give the median and mean titers of individuals, respectively. Variability in titer is shown by plotting the first and third quartiles of the titers as the outer limits of the box. Points beyond the whiskers denote outliers. Groups were compared by two-tailed, unpaired t test, and false discovery rate-adjusted P values are indicated.