Drive through covid testing orlando1/24/2024 The WHO published interim guidance in October 2021 highlighting that despite hundreds of Ag-RDT brands available on the market, the number of those examined in published reports is still relatively limited ( 6). There is a myriad of Ag-RDTs on the market however, their performance varies between brands ( 5). Most Ag-RDTs are based on lateral flow immunoassays where a nitrocellulose membrane presents antibodies that capture viral antigens, usually the SARS-CoV-2 Nucleocapsid (N) protein. Their utility has been demonstrated in the United Kingdom, where they were able to expand the number of people tested, thus playing a crucial role in restraining virus transmission ( 4). In this scenario, rapid diagnostic tests (RDTs) based on the detection of SARS-CoV-2 antigens (Ag-RDTs) offer a faster and less expensive option for SARS-CoV-2 detection. Altogether, these limitations hamper timely case isolation and the control of virus transmission locally. Additionally, RT-qPCR is expensive and requires sophisticated equipment and highly trained technicians, which prevent its deployment in low-resource and remote settings. However, throughout the pandemic there have been consistent reports of a delay in results due to slow turnaround times attributed to the transportation of samples to specialized laboratories and sample processing. Reverse transcription-quantitative PCR (RT-qPCR) is the gold-standard technique for SARS-CoV-2 diagnosis, and both the United Kingdom and Brazil quickly implemented large-scale RT-qPCR testing for COVID-19 diagnosis such as the National Test and Trace programs implemented in many countries ( 3). While viral evolution is inevitable and a small number of variants of concern (VOCs) monopolize SARS-CoV-2 transmissibility potential ( 2), SARS-CoV-2 still poses a significant threat to human life and timely detection of positive cases is vital. Despite widespread vaccination programs, SARS-CoV-2 breakthrough infections are commonly reported among the vaccinated. The COVID-19 pandemic represents the worst health crisis of the last century and has claimed more than 5 million reported lives globally since December 2019 ( 1), with the true number likely much greater. We present an independent review of the Novel Coronavirus 2019-nCoV Antigen Test (Colloidal Gold) (Beijing Hotgen Biotech Co., Ltd.), at two sites within Brazil and one in the United Kingdom. Thus, there is now a need for a transparent evaluation of Ag-RDTs with both analytical and clinical evaluation. Many of these Ag-RDTs have not been externally evaluated, and results are not readily available to the public. Similarly in Brazil, as of January 2022, pharmacies and other health care retailers are permitted to sell Ag-RDTs directly to the community. However, as this has now ceased, individuals are responsible for their own acquisition of test kits. In the United Kingdom, this was somewhat controlled indirectly as the government offered free tests from a small number of companies. IMPORTANCE Since the beginning of the SARS-CoV-2 pandemic, we have witnessed growing numbers of antigen rapid diagnostic tests (Ag-RDTs) being brought to market. This study illustrates the comparative performance of the Hotgen Ag-RDT across two global settings and considers the different approaches in evaluation methods. Overall, while a higher sensitivity was claimed by the manufacturers than that found in this study, this evaluation finds that the Ag-RDT meets the WHO minimum performance requirements for sensitivity and specificity of COVID-19 Ag-RDTs. The analytical limit of detection was determined as 1.0 × 10 3 PFU/mL (Alpha), 2.5 × 10 2 PFU/mL (Delta), 2.5 × 10 3 PFU/mL (Gamma), and 1.0 × 10 3 PFU/mL (Omicron), giving a viral copy equivalent of approximately 2.1 × 10 4 copies/mL, 9.0 × 10 5 copies/mL, 1.7 × 10 6 copies/mL, and 1.8 × 10 5 copies/mL for the Ag-RDT, respectively. An overall sensitivity and specificity of 88.2% (95% confidence interval, 81.3 to 93.3) and 100.0% (95% CI, 99.1 to 100.0), respectively, were obtained for the Brazilian and UK cohorts. Analytical evaluation of the Ag-RDT was performed using direct culture supernatants of SARS-CoV-2 strains from the wild-type (B.1), Alpha (B.1.1.7), Delta (B.1.617.2), Gamma (P.1), and Omicron (B.1.1.529) lineages. The collected samples (446 nasal swabs from Brazil and 246 nasopharyngeal samples from the UK) were analyzed by the Ag-RDT and compared to reverse transcription-quantitative PCR (RT-qPCR). This report describes the clinical evaluation of the Novel Coronavirus 2019-nCoV Antigen Test (Colloidal Gold) (Beijing Hotgen Biotech Co., Ltd.), at two sites within Brazil and one in the United Kingdom. The COVID-19 pandemic has led to the commercialization of many antigen-based rapid diagnostic tests (Ag-RDTs), requiring independent evaluations.
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