Evaluation of SARS-CoV-2 IgG antibody response in PCR positive patients: comparison of nine tests in relation with clinical data

Naaber, P.; Hunt, K.; Pesukova, J.; Haljasmagi, L.; Rumm, P.; Peterson, P.; Hololejenko, J.; Eero, I.; Jogi, P.; Toompere, K.; Sepp, E.

Background. High number of SARS-CoV-2 antibody tests are available in different formats, detect different types of antibodies, and use different target proteins. Sensitivity of these tests varies and could be also related to clinical symptoms and testing time. Methods. Serum samples from 97 COVID-19 patients and 100 controls were tested with 9 antibody tests (SNIBE, Epitope, Euroimmun, Roche, Abbott, DiaSorin, Biosensor, LIPS N, and LIPS S-RBD). The results were analyzed in context of clinical data. Findings. Positivity rate was of tests was following: N-LIPS test (91.8% cases), Epitope (85.6%), Abbott and in-house LIPS S-RBD (both 84.5%), Roche (83.5%), Euroimmun (82.5%), DiaSorin (81.4%), SNIBE (70.1%), and Biosensor (64.9%). Agreement between tests varied (71-95%). Correlation between patient symptoms score and antibody value was test-dependent: varied from strongest in LIPS N (rho=0.41; p<0.001) to nonsignificant (LIPS S-RBD). Testing time from symptoms influenced sensitivity in some tests more than anothers. Interpretation. Sensitivity of tests varied highly and combination of different tests may improve it. Relation of results to symptoms and testing time was test-dependent. Thus, some antibody tests seems to be more sensitive to detect antibodies early and in asymptomatic patients than others. Funding. Study was funded by SYNLAB Estonia and Estonian Research Council grant PRG377.