Active serological surveillance for viral antibodies is of great importance for influenza control and prevention. Several IAV subtype-specific serological tests have been developed. At present, subtyping of IAV mainly relies on a hemagglutination inhibition (HI) test using HA and NA subtype-specific reference sera [15] . However, there are a number of drawbacks to HI testing. This assay is 1) relatively laborious; 2) low in sensitivity; 3) requires preparation of antigen from viable viruses which are potentially hazardous and 4) contains low signal to noise ratio, e.g. the assay exhibits inter-variability and subtype cross-reactivity [16, 17] . Moreover, the HI test can be confounded by steric hindrance from NA antibodies, leading to nonspecific inhibition and misidentification [18] .