Method for determining immune competence against severe acute respiratory syndrome coronavirus 2

A method for determining immune competence against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), comprising:

• obtaining a blood sample from a test subject in need thereof;
• detecting, in the blood sample, titers of binding antibodies against SARS-CoV-2 spike subunit 1 (S1) protein and receptor binding domain (RBD) protein thereof;
• calculating an estimated value of a neutralizing antibody titer against SARS-CoV-2 by substituting the titers of the binding antibodies into a linear regression model having the following equation (I):
• A=−0.4306+0.4121×B+2.8792×C (I)
• where A=estimated value of neutralizing antibody titer against SARS-CoV-2
• B=binding antibody titer against S1 protein
• C=binding antibody titer against RBD protein;
• comparing the estimated value of the neutralizing antibody titer against SARS-CoV-2 with a predetermined standard obtained from a subject having protective immunity or sterilizing immunity against SARS-CoV-2,
• wherein when the estimated value of the neutralizing antibody titer against SARS-CoV-2 is less than the predetermined standard, the test subject is determined as having an insufficient neutralizing antibody titer against SARS-CoV-2 which is indicative of having neither protective immunity nor sterilizing immunity against SARS-CoV-2;
• and
• inoculating the test subject having neither protective immunity nor sterilizing immunity against SARS-CoV-2 with a vaccine against a SARS-CoV-2 variant, thereby increasing the test subject's immune competence.