Fig. 2. Cross-reactive antibody responses.

Cross-reactive antibody responses were determined by haemagglutination inhibition a Groups that did not show any cross-reaction were left out. Presented are the individual titers, geometric means, and SDs. Horizontal dotted line: detection limit. Significant lower responses compared to the homologous strains are indicated by *(p < 0.05) and **(p < 0.01), by the WMW test. split vaccines alone: 45 µg HA—blue circles, 15 µg HA—red triangles, or the SWE-adjuvanted split vaccines: 15 µg HA—green open circles, 7.5 µg HA—purple diamonds. A phylogenetic tree of the divergent strains tested for cross-reactivity is shown in b. H7 HA’s are divided in two lineages, the Eurasian and North American lineage. The numbers indicate branch length.