The five health care staff had been definitively seronegative in opposition to H5 in all assays, meaning they weren't infected with H5. Hemagglutinin inhibition (Hello) assay: The Hello assay checks for antibodies into the hemagglutinin of the specific influenza virus employing purple blood cells (RBC). Many different types of RBCs https://www.dailypioneer.com/2016/state-editions/chit-fund-hc-rejects-indu-dewans-bail-plea.html