Neutralizing antibody (NAb) can block the interaction between the receptor-binding domain (RBD) of the novel coronavirus spike protein with the ACE2 cell surface receptor. The level of NAb, therefore, can be used to analyze a patient’s immunity against future SARS-CoV-2 infection. The conventional antibody test only indicates whether antibodies are present in the body or not. While this test gives quantitative results in BAU/ml. It tests give actual levels of antibodies present, which could assist you in deciding whether you require further vaccinations or not.