Validation of Roche immunoassay for severe acute respiratory coronavirus 2 in South Africa

Abstract

Background: Serology testing is an important ancillary diagnostic to the reverse transcriptase polymerase chain reaction (RT-PCR) test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to evaluate the performance of the Roche Elecsys™ chemiluminescent immunoassay (Rotkreuz, Switzerland), that detects antibodies against the SARS-CoV-2 nucleocapsid antigen, at an academic laboratory in South Africa.Methods: Serum samples were collected from 312 donors with confirmed positive SARS-CoV-2 RT-PCR tests, with approval from a large university’s human research ethics committee. Negative controls included samples stored prior to December 2019 and from patients who tested negative for SARS-CoV-2 on RT-PCR and were confirmed negative using multiple serology methods (n = 124). Samples were stored at –80 °C and analysed on a Roche cobas™ 602 autoanalyser.Results: Compared with RT-PCR, our evaluation revealed a specificity of 100% and overall sensitivity of 65.1%. The sensitivity in individuals 14 days’ post-diagnosis was 72.6%, with the highest sensitivity 31–50 days’ post-diagnosis at 88.6%. Results were also compared with in-house serology tests that showed high agreement in majority of categories.Conclusions: The sensitivity at all-time points post-diagnosis was lower than reported in other studies, but sensitivity in appropriate cohorts approached 90% with a high specificity. The lower sensitivity at earlier time points or in individuals without symptomatology may indicate failure to produce antibodies, which was further supported by the comparison against in-house serology tests.

Sentinel seroprevalence of SARS-CoV-2 in Gauteng Province, South Africa, August - October 2020

“…In summary, this revealed a high cumulative specificity compared with PCR testing of 100% and a sensitivity which varied from 47.6% in patients prior to day 7 post diagnosis to 90% after 30 days in patients with PCRconfirmed SARS-CoV-2 infection. [14]…”

The Performance of Diagnostic Tests for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in the South African Population: A Scoping Review

“…Figure 1 shows the identification, screening, eligibility, and inclusion of the studies for the scoping review [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. The quality assessment of the 17 articles resulted in four articles scoring 71% and the rest scoring 86% and above.…”

“…Table 1 provides an overview of the testing kits or methodology evaluated. Seven of the 17 studies included populations from Gauteng [ 17 , 19 , 21 , 22 , 24 , 29 , 30 ], four from the Western Cape [ 15 , 16 , 26 , 28 ], one from Limpopo [ 14 ], one from Eastern Cape [ 18 ], and one from the Free State [ 23 ]. Of the remaining three studies, two studies included samples from more than one province [ 20 , 27 ] and one study undertook testing on stored samples [ 25 ].…”

Epidemiology and outcomes of SARS-CoV-2 infection associated with anti-nucleocapsid seropositivity in Cape Town, South Africa

“…Prior infection with SARS-CoV-2 was assessed through detection of total anti-nucleocapsid (anti-N) antibody using the Elecsys™ anti-N SARS-CoV-2 assay (Roche, Geneva, Switzerland) on the Roche Cobas e601 platform according to manufacturer's instructions. The assay is widely used for population seroprevalence studies and its performance was evaluated in South Africa where the specificity was 100% and sensitivity was 89% for detection of PCR-confirmed infection >30 days post diagnosis (14). The assay was deemed adequate for Section 21 use in serosurveys by the South African Health Products Regulatory Authority.…”