SARS-CoV2 serology assays: utility and limits of different antigen based
tests through the evaluation and the comparison of four commercial tests
Abstract
Introduction: SARS-CoV2 serology testing is multipurpose provided to
choose an efficient test. We evaluated and compared 4 different
commercial serology tests, three of them had the Food and Drug
Administration (FDA) approval. Our goal was to provide new data to help
to guide the interpretation and the choice of the serological tests.
Methods: Four commercial tests were evaluated: Cobas®Roche®(total anti-N
antibodies), VIDAS®Biomerieux®(IgM and IgG anti-RBD antibodies),
Mindray®(IgM and IgG anti-N and anti-RBD antibodies) and Access®Beckman
Coulter®(IgG anti-RBD antibodies). Were tested: a positive panel (n=72
sera) obtained from COVID-19 confirmed patients and a negative panel
(n=119) of pre-pandemic sera. Were determined the analytical
performances and was drawn the ROC curve to assess the manufacturer’s
threshold. Results: A large range of variability between the tests was
found. Mindray®IgG and Cobas® tests showed the best overall sensitivity
79,2%CI95%[67,9-87,8]. Cobas® showed the best sensitivity after
D14; 85,4%CI95%[72,2-93,9]. The best specificity was noted for
Cobas®, VIDAS®IgG and Access® IgG(100%CI95%[96,9-100]). Access®
had the lower sensitivity even after D14 (55,5% CI95%[43,4-67,3]).
VIDAS®IgM and Mindray®IgM tests showed the lowest specificity and
sensitivity rates. Overall, only 43 out of 72 sera gave concordant
results (59,7%). Retained cut-offs for a significantly better
sensitivity and accuracy, without altering significantly the
specificity, were: 0,87 for Vidas®IgM(p=0,01), 0,55 for
Vidas®IgG(p=0,05) and 0,14 for Access®(p<10-4). Conclusion:
Although FDA approved, each laboratory should realize its own evaluation
for commercial tests. Tests variability may raise some concerns that
seroprevalence studies may vary significantly based on the used serology
test.