Field performance evaluation of the PanBio rapid SARS-CoV-2 antigen assay in an epidemic driven by the B.1.351 variant in the Eastern Cape, South Africa

Abstract

Background South Africa was the African country with the most recorded cases of SARS-CoV-2 during 2020, experiencing 2 waves of infection. During the first wave, diagnostics were largely based on reverse transcription-linked PCR (RT-PCR). The Abbott PanBio antigen test was deployed during the 2nd wave which may have been driven by emergence of the B.1.351 variant. At the time of evaluation in mid-November 2020, B.1.351 was the dominant circulating virus in Nelson Mandela Bay, in the Eastern Cape Province. Methods Used PanBio antigen swabs (collected from patients with genetically characterised virus) were first validated as suitable for PCR. A prospective study was then undertaken to evaluate assay performance in the field. Testing was conducted at mobile community testing centres on 677 ambulant patients. Used swabs were kept and tested by RT-PCR. Results During initial validation, used swabs in proprietary lysis buffer were found to be suitable for PCR and secondly, the PB assay reliably detected patients infected with B.1.351. In the field study, of 146 RT-PCR positive individuals, 101 were RTD positive in the clinic. The RTD had a sensitivity of 69.2% (95%CI 61.4, 75.8) and specificity of 99.0% (95%CI 98.8, 99.3). Sensitivity was dependent on the amount of viral RNA in clinical samples, as reflected by the PCR cycle threshold (CT) value. Conclusions The assay reliably detected B.1.351 infections in ambulatory ill patients during initial validation and in field testing. In the field, assay sensitivity was >90% in patients with high viral loads who are expected to be most infectious. Negative and positive predictive values were also >90%.

Evaluating diagnostic accuracies of Panbio™ COVID-19 rapid antigen test and RT-PCR for the detection of SARS-CoV-2 in Addis Ababa, Ethiopia using Bayesian Latent-Class Models (BLCM)

“…Also there was a single false positive report from the total non-diseased of 242. The low frequency of false positive report of the AG-RDTwas in line with a study done by Bulilete and colleagues in Spain and Akingba and colleagues, in south Africa, while we consider RT-PCR as gold standard [38,39].…”

“…with sensitivity and specificity ranges of 71.4%-91.7% and 94.9%-100%, respectively, while using RT-PCR as a gold standard. These study results also considered Ct values of <30 that yielded test sensitivities from 87.7% to 97.8% [36][37][38].…”

The accuracy of novel antigen rapid diagnostics for SARS-CoV-2: a living systematic review and meta-analysis

“…After removing duplicates, 8,921 articles were screened, and 266 papers were considered eligible for full-text review. Of these, 148 were excluded because they did not present primary data [13,19–131] or the Ag-RDT was not commercially available [16,132–164], leaving 133 studies to be included in the systematic review (Fig 1) [4,165–296].…”

Clinical Performance of Rapid and Point-of-Care Antigen Tests for SARS-CoV-2 Variants of Concern: A Living Systematic Review and Meta-Analysis

“…Regarding the reference standard risk of bias, two studies [ 29 , 30 ] had a high risk of bias because the results of the RATs were told to the participants before the rRT-PCR was performed. Unclear risks of applicability concerns were assigned to two studies [ 20 , 31 ] adopting in-house rRT-PCR assays.…”

“…In this study based on a living systematic review and meta-analysis, the evidence of the diagnostic utility of RATs without instruments for SARS-CoV-2 variants of concern were combined and compared according to the presence of symptoms. The pooled sensitivity and specificity of RATs for variants from 6904 participants in six studies [ 19 , 20 , 28 , 29 , 30 , 31 ] were 69.7% and 100.0%, respectively. The reported sensitivities of symptomatic patients were higher than those of asymptomatic individuals.…”