Serum ADCC titers weakly correlate with protection against H1N1 and H5N1 challenges.

<p>ADCC titers against (<b>A</b>) A/California/07/2009 (H1N1) and (<b>C</b>) A/Hong Kong/156/97 (H5N1) were determined. Titers for mice that survive challenge (open triangles) and mice that succumb to infection (closed triangles) are presented separately for pre-vaccination (pre) and post-vaccination (post) sera. Assay background level is indicated with dashed line in panels A and C. Vaccine homologous H1 ADCC titers are higher in post-vaccination serum (p<0.001, t-test). H5 ADCC titers are detectable in pre-vaccination samples and increase significantly after vaccination (p<0.001, t-test). ROC curves were calculated to assess the correlation (<b>B</b>) between H1N1 ADCC titer and protection against homologous H1N1 challenge (ROC area = 0.71, p<0.05, 95% CI 0.55–0.87) and (<b>D</b>) between H5N1 ADCC titer and protection against H5N1 challenge (ROC area = 0.67, p<0.05, 95% CI 0.505–0.84).