ABSTRACT
The circulation of certain SARS-CoV-2 variants may have a great impact on the epidemiological status of a geographical area; therefore, it is important that their presence is monitored. Currently, the gold standard method used to identify newly emerged variants is sequencing of either genes or whole genomes. However, since this method is relatively expensive and has a long turnaround time, other rapid strategies should also be employed. The current study aimed to evaluate the performance of the Simplexa® SARS-CoV-2 Variants Direct assay, which is a RT-PCR that determines the variant present in a nasopharyngeal swab sample in approximately two hours. Totally, 527 positive samples for SARS-CoV-2 were analyzed from January until December 2022 and next-generation sequencing (NGS) was used as the reference method. The assay showed high sensitivity, ranging from 94.12 % to 100 %, depending on the variant. The assay also showed high specificity, reaching 100 % for Delta and BA.1 variants, and 99.74 % and 98.67 % for BA.2 and BA.4/BA.5 variants, respectively. Moreover, the assay was able to identify the correct variant category in the presence of any subvariant in the sample. We conclude that the assay can be used to facilitate faster monitoring of circulating SARS-CoV-2 variants, however sequencing cannot be completely replaced, since new variants always emerge, and constant updates are needed, so that the user is able to interpret the melting curve patterns.
ABSTRACT
In the summer of 2019, DiaSorin Molecular started designing a multiplex respiratory panel with pan-coronavirus detection as one of the planned targets. The R&D team in Gerenzano, Italy was already searching databases, performing alignments and assessing preliminary target regions for common coronavirus RT-PCR, including SARS and MERS-CoV. In December 2019, we were vigilant and following a cluster of pneumonia cases with undetermined etiology in Wuhan, China. As we now know, the cause of the respiratory infections was the new SARS-CoV-2 virus. DiaSorin Molecular swiftly responded in line with our heritage and company history in detecting emerging infectious diseases. Early in the pandemic and in record time, using research and development teams in both Italy and the U.S. together with the U.S. manufacturing team, we were able to develop and commercialize a new diagnostic test, Simplexa™ COVID-19 Direct, to detect SARS-CoV-2. Our unique platform allowed development of a rapid diagnostic test without the need for extraction reagents. Challenges with control materials, quarantines, clinical samples, raw materials and production were overcome and the entire company worked side by side for accelerated delivery of this assay to clinical labs in Europe, the U.S. and Canada.