Quantitation and analysis of the specificity of post-immunization antibodies to influenza B viruses using single radial haemolysis.

The single radial haemolysis (SRH) technique detected anti-B/HK/8/73 HA antibody rises in 59-85% of paired sera from persons immunized with different influenza vaccines. In contrast, analysis of the same sera by the haemagglutination inhibition (HI) test indicated significant antibody rises in only 27-54% of paired sera. High levels of antibody were detected to influenza B/HK/8/73 and B/Singapore/222/79 viruses in post-immunization sera analysed by SRH, whereas the HI test indicated comparatively low geometric means antibody titres. Most adults responded to immunization with influenza B virus by producing cross-reactive (CR) antibody which reacted with different influenza B viruses including the early isolate B/Lee/40.