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Samples were collected in serum separator tubes (Beckton Dickinson, Franklin Lakes, New Jersey), centrifuged at 1811 g for 8 minutes, and after clinical testing residual sera were collected in accordance with previously described laboratory protocols for COVID-19 sample handling. We prospectively selected samples between March 30, 2020, to May 15, 2020, from COVID-19 patients in our institution on the basis of at least 1 positive RT-PCR respiratory sample being positive on our cobas 6800 SARS-CoV-2 assay (Roche Diagnostics, Rotkruez, Switzerland), with the cycle threshold value being lower than cutoff. MATERIALS AND METHODSĪ total of 333 unique, nonduplicated serum samples obtained from COVID-19–confirmed patients (n = 170) and negative controls (n = 163) obtained before December 2019, before the COVID-19 pandemic, were used in the study.
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Because the COVID-19 situation is rapidly evolving, there is a need to inform laboratory users of potential differences in the interpretation of SARS-CoV-2 serology assays. Chew et al 6 and Tang et al 7 had previously shown that Abbott performed reasonably well, with a duration of 14 days being suggested as a minimum period to test symptomatic COVID-19 patients for the presence of antibodies. In this study, we sought to compare the diagnostic accuracy of two commercially available, automation-track–compatible SARS-CoV-2 serology assays, namely the Roche Elecsys and Abbott Architect Anti-SARS-CoV-2 assays. 4, 5 A plethora of serology kits have now entered the market, often with claims of good performance, many also having obtained provisional US Food and Drug Administration approval or Conformitè Europëenne marking. Serologic tests detect antibodies in the host as immunoglobulin (Ig) G, IgM, and/or IgA to SARS-CoV-2, contributing to the identification of individuals who have been exposed to COVID-19, possibly obtaining immunity and further assisting in containment or isolation strategies or even the idea of “immune passports.” Zhao and colleagues 4 have recently shown that the median seroconversion times for IgM and IgG were 11 days and 12 days, respectively, and that specific IgG antibodies to SARS-CoV-2 remain detectable in COVID-19 patients during the symptomatic phase of the disease even after RNA becomes undetectable. Coupled with limited RT-PCR reagent/kit availability, there have been some initiatives to use SARS-CoV-2 serology as a screening test or for surveillance within a population. 3 Polymerase chain reaction–based molecular testing turnaround time varies from a few hours to days, taking into consideration the expertise of the laboratory in question, as well as the workload, type, and throughput of the analyzers in operation. 2 The gold standard laboratory diagnosis of COVID-19 relies on the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid by real-time reverse transcription polymerase chain reaction (RT-PCR) based on gene targets such as N, E, RdRp, orf1a, and orf1b genes.
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1 COVID-19 patients may present with nonspecific symptoms ranging from mild respiratory tract illness to severe pneumonia requiring intensive care support, hence posing diagnostic difficulties to the clinician. Coronavirus disease 2019 (COVID-19) has now been declared a public health pandemic by the World Health Organization (WHO) after its initial outbreak in Wuhan, China.