A multicentre study comparing post-mortem SARS-CoV-2 antibody testing in Cape Town mortuaries.

Abstract

Background: Coronavirus disease 2019 (COVID-19) was recognised as a global pandemic in 2019, yet the exact number of infections is still unclear. In addition, there is limited research on post-mortem antibody testing.

Objectives: This study sought to evaluate the use of the SureScreen COVID-19 immunoglobulin (Ig) G and IgM Rapid Test Cassette in deceased individuals by comparing it to the gold-standard antibody tests in South Africa, and to identify the most appropriate antibody testing method for post-mortem samples.

Method: Between May 2021 and February 2023, fifty cases, with suspected COVID-19 infection during their lifetime, were recruited from Tygerberg Mortuary and Salt River Mortuary, after obtaining informed consent from their next-of-kin. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was confirmed through antemortem positive COVID-19 polymerase chain reaction (PCR) (PCP) tests in 39 participants. Blood samples were collected during autopsies in serum separator tubes, which yielded better separation when centrifuged immediately after collection. The SureScreen test was performed alongside Roche Diagnostics Elecsys Anti-SARS-CoV-2 and Abbott Architect SARS-CoV-2 IgG assays.

Results: Among the confirmed PCP cases, Elecsys demonstrated the highest sensitivity (97.1%) followed by SureScreen IgG (82.1%). In a logistic regression analysis, PCP confirmation was significantly associated with the SureScreen IgG results (p < 0.05).

Conclusion: Overall, Roche's Elecsys had the highest yield of positive results on our cohort of post-mortem serum samples, followed by SureScreen, and finally, Abbott's Architect assay.

Contribution: These results suggest that the SureScreen test has potential as a screening tool in mortuary settings, with Roche's Elecsys assay recommended for diagnostic confirmation.