SARS-CoV-2 antibody response dynamics and heterogeneous diagnostic performance of four serological tests and a neutralization test in symptomatic healthcare workers with non-severe COVID-19
SARS-CoV-2 neutralizing antibodies were present in about 85% of symptomatic healthcare workers with non-severe COVID-19.
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SARS-CoV-2 antibody levels remained stable up to 4 - 6 months after infection.
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There is large variability in diagnostic test performance between ELISA tests.
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The Wantai ELISA performed best and had almost perfect agreement with virus neutralizing tests.
Abstract
Background
Most COVID-19 patients experience non-severe illness. The presence of SARS-CoV-2 antibodies suggest possible protection against re-infections in prior SARS-CoV-2 infected individuals.
Objectives
The aims of this prospective observational study were to longitudinally assess the antibody response during the first 4–6 months after polymerase chain reaction (PCR) confirmed SARS-CoV-2 infection, and to study the diagnostic performance of four different enzyme-linked immunosorbent assays (ELISAs) and a surrogate virus neutralization test (sVNT) in symptomatic healthcare workers (HCWs) with non-severe COVID-19.
Study design
HCWs in a teaching hospital were included between March 8 and June 15, 2020, when they had a PCR-confirmed SARS-CoV-2 infection in the past 3 months. The performances of four ELISAs (Wantai, Bio-Rad Platelia, BioTrading Immy clarus, and Euroimmun) were evaluated in serum samples obtained at the moment of study inclusion and subsequently at 1, 2 and 3 months thereafter. Furthermore, in the last available serum sample sVNT by GenScript was performed.
Results
309 samples from 80 positive HCWs were included of whom 70 (88%) were SARS-CoV-2 seropositive. The detection rates of SARS-CoV-2 antibodies by the different ELISAs were heterogenous ranging from 64% for the Euroimmun ELISA to 88% for the Wantai ELISA. The Wantai ELISA had the highest and almost perfect agreement with sVNT (96%, Cohen's kappa 0.83).
Conclusion
SARS-CoV-2 (neutralizing) antibodies were detectable in most symptomatic individuals with non-severe COVID-19. The presence of antibodies remained stable up to six months after initial infection. There is large variability in diagnostic test performance between ELISA tests.
