Figure 1
Cross-reactive hemagglutination inhibition (HAI) responses against the latest epidemic influenza A (H3) isolates in humans vaccinated with the 2014–15 Northern Hemisphere (NH) seasonal influenza vaccines.
Sera were collected from healthy children (6 months to <9 years), adults (18 to <65 years) and older adults (≥65 years), vaccinated with 2014–15 NH egg- or cell-based vaccine. Post-vaccination (post-vac) HAI titers against the H3 vaccine prototype virus and representative isolates of the latest H3N2 epidemic strains were determined by using 1% guinea pig erythrocytes. There were 30 post-vac sera each from adult and older adult populations and 52 post-vac sera from children administered 2014–15 NH egg-based vaccine. There were also 24 post-vac sera each from adult and older adult populations administered 2014–15 NH cell-based vaccine. The H3 strains in the testing panel were as follows: egg-grown A/Texas/50/2012 (TX/12e), A/Switzerland/9715293/2013 (SWZ/13e), A/Palau/6759/2014 (PL/14e), A/North Carolina/13/2014 (NC/14e) and cell-grown A/Texas/50/2012 (TX/12c), A/Switzerland/9715293/2013 (SWZ/13c), A/North Carolina/13/2014 (NC/14c) and A/Michigan/15/2014 (MI/14c). *Indicates the H3 prototype virus of 2014–15 NH egg-based vaccine. Cross-reactive post-vac geometric mean titers (GMTs) against testing H3 viruses are expressed as % of TX/12e post-vac GMT in the bar graphs. Numbers shown at the bottom of each bar graph are individual post-vac GMTs and GMT ratios relative to TX/12e. Red dashed horizontal line indicates 50% of TX/12e-specific GMT.
