Comparison of single radial immunodiffusion, SDS-PAGE and HPLC potency assays for inactivated influenza vaccines shows differences in ability to predict immunogenicity of haemagglutinin antigen.

•Two potential alternative influenza vaccine potency assays were compared with SRD.•Forced degradation experiments showed differences between assays.•Physico-chemical methods could not detect loss of potency as shown by SRD.•Potency measured by physico-chemical methods did not correlate with immunogenicity.