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SARS-CoV-2 antibody tests are available in various formats, detecting different viral target proteins and antibody subclasses. The specificity and sensitivity of SARS-CoV-2 antibody tests are known to vary and very few studies have addressed the performance of these tests in COVID-19 patient groups at different time points. We here compared the sensitivity and specificity of seven commercial (SNIBE, Epitope, Euroimmun, Roche, Abbott, DiaSorin, Biosensor) and two in-house LIPS assays (LIPS N and LIPS S-RBD) IgG/total Ab tests in serum samples from 97 COVID-19 patients and 100 controls, and correlated the results with the patients' clinical data and the time-point the test was performed. We found a remarkable variation in the sensitivity of antibody tests with the following performance: LIPS N (91.8%), 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%). The overall agreement between the tests was between 71-95%, whereas the specificity of all tests was within 98-100%. The correlation with patients' clinical symptoms score ranged from strongest in LIPS N (ρ = 0.41; p

SummaryBackgroundHigh 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.MethodsSerum 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.FindingsPositivity 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 (ρ=0.41; pInterpretationSensitivity 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.FundingStudy was funded by SYNLAB Estonia and Estonian Research Council grant PRG377.Research in contextEvidence before this studyHigh variation in COVID-19 antibody tests sensitivity has been described. Relation between antibody response and clinical cause has been found in some studies but not in others. It’s known that antibody response is time dependent, however seroconversion medians varied in different studies.Added value of this studyWe confirmed that SARS-CoV-2 antibody response depends on clinical symptoms and time of testing, but we also found that this relation is dependent on test setup and viral antigens used in the tests. This may explain contradictory results of previous studies.Implications of all the available evidenceOur study has practical implications showing that not all antibody tests work uniformly well in symptomatic and asymptomatic cases and in different time periods from disease onset. This should be taken into consideration in clinical practice for diagnosing COVID-19 and in epidemiological studies evaluating the seroprevalence especially in asymptomatic population.