< 50.0 AU/ml – negative
≥ 50.0 AU/ml – positive (upper limit of determination is 40 000 AU/ml)
A subsequent negative antibodies result does not preclude an initial positive nasopharyngeal swab (PCR) result, as asymptomatic/mildly symptomatic people may not develop antibodies.
SARS coronavirus 2 IgG QN result is below the reference value
This means that there are not enough IgG antibodies for the coronavirus SARS-CoV-2 in the body to confirm that the patient has recovered from COVID-19 or to confirm the efficiency of vaccination. It cannot be excluded that the patient is in an early stage (weeks 1–2) of the disease, where antibodies have not yet formed. In addition, some people do not develop a measurable level of antibodies, e.g., patients who are asymptomatic, have only mild symptoms or immune deficiency. After recovering from the disease, the level of antibodies can decrease in time and this may also influence the test result. After vaccination, it may take weeks until antibodies are formed in blood.
SARS coronavirus 2 IgG QN result is above the reference value
A positive result means that you have IgG antibodies to the coronavirus SARS-CoV-2 and that you have either had COVID-19 disease or developed antibodies after vaccination. The result indicates the presence of immunity. Higher antibody values are associated with a stronger immune response, but based on current knowledge we cannot predict the duration of immunity or the risk of re-infection based on antibody levels.
The Abbott SARS-CoV-2 IgG QN assay used in SYNLAB is presented in AU/ml (arbitrary units/ml). The results of antibody tests from different manufacturers are not directly comparable. To convert our test result to BAU/ml (Binding Antibody Units/ml) as suggested by WHO, the following equation should be used: BAU/ml = 0.142 x AU/ml.