Vaccine immunogenicity assessed by HI assay - per protocol population.

1n/N: responders (n) as proportion of the (sub-)population (N).2GMT: geometric mean titer;395% CI: 95% confidence interval.4Seroprotection rate: proportion of subjects with a protective titer pre- or post-vaccination (titer ≥40).5Seroconversion rate: proportion of subjects with antibody increase from 6Significant increase: proportion of subjects with an antibody titer of ≥10 pre-vaccination and 4-fold antibody increase post-vaccination.7CHMP criteria.8GM increase = geometric mean increase.