key: cord-1056076-hl9ec5zb
authors: Shipman, Kate E; Weaving, Gary; Cromwell, Tamsyn
title: Identification of analytical issues in method verification of SARS CoV-2 serology
date: 2020-07-28
journal: Ann Clin Biochem
DOI: 10.1177/0004563220944973
sha: baf5c22cf4c3c2edfda891bb65b7bec989bfc0da
doc_id: 1056076
cord_uid: hl9ec5zb

nan

In the PHE validation, the majority of results showed good discrimination between values. On the Roche platform, at time of writing, of 2055 tests run, the probability of getting a value <1.0 but >0.2 is <1%. Likewise, on the Abbott method, results around the cut-off are hard to find.

Results were correlated with RNA PCR results; unsurprisingly, those with confirmed PCR COVID infections were strong positives on both antibody assays. However, out of an initial verification set of 52 confirmed PCR-positive samples, one gave a 'not detected' antibody result on the Roche assay. During routine use, a further two PCR-positive patients on the Roche have tested antibody negative. At 62, 60 and 45 days postpositive swab, the Roche results were 0.08, 0.18 and 0.247, respectively. Similar cases have been identified on the Abbott system.

It may be that some cases were caught early, prior to seroconversion, or late when the antibody response had faded. This may also account for the rarity of intermediate values. Alternative explanations include the possibility that the PCR result may have been a falsepositive, or that not all individuals produce antibodies detectable by the current methods available (confirmed in PHE validation). Further data will be reviewed locally, and trials are being set up nationally to review the natural history of antibody status. We would encourage such studies in order to identify the reasons for discrepancies either biological or analytical.

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The author(s) received no financial support for the research, authorship, and/ or publication of this article.

Not applicable. 

COVID-19: laboratory evaluations of serological assays

The measurement of observer agreement for categorical data

GraphPad QuickCalcs: quantify interrater agreement with kappa

SARS-CoV-2 IgG Abbott Architect kit insert. Ref 6R86-22, 6R86-32

Elecsys Anti-SARS-CoV-2 Roche kit insert

We would like to thank the laboratory staff and network for their hard work and support.