“TwinDemic" Diagnostic System Rapidly and Simultaneously Detects SARS-CoV-2 and Influenza A Virus

The COVID-19 pandemic in 2019 sparked efforts to raise public awareness about pandemics and led to accelerated vaccine development. While these actions effectively reduced viral transmission, they also resulted in unintended consequences, such as a decrease in the spread of other viruses and disruptions in vaccination schedules. However, rapidly mutating pathogens like viruses remain a significant threat, with predictions suggesting future co-infections could lead to "twindemics" or "tripledemics." Reverse Transcriptase-quantitative PCRs (RT-qPCRs) are reliable diagnostic assays, but their reliance on expensive equipment and reagents limits their use in resource-limited settings. This creates a need for a rapid, sensitive, and accurate molecular diagnostic tool capable of detecting multiple viruses at the point-of-care. To address this need, a novel tool has been developed for the simultaneous and rapid detection of SARS-CoV-2 and influenza A virus.

Researchers from Incheon National University (INU, Incheon, South Korea) have developed the TwinDemic Detection (TDD) system, a point-of-care diagnostic tool that uses a novel, non-enzymatic signal amplification method. The TDD system includes a transparent poly (methyl methacrylate) microfluidic chip with hydrogel-based, enzyme-free gene detection sensors, along with a handheld fluorescence reader. These hydrogel chambers are embedded with customized probes designed to detect the target viral pathogens, SARS-CoV-2 and influenza A. The reaction between the target viral DNA and the specific probe amplifies the fluorescence signal. The TDD system is user-friendly, cost-effective, and has a detection limit of 0.46 picomolar (pM) for SARS-CoV-2 and 0.39 pM for influenza A virus. When tested with human nasopharyngeal samples, TDD was shown to simultaneously detect both SARS-CoV-2 and influenza A, demonstrating its potential for rapid on-site testing of a wide range of viruses.

Image: The rapid, accurate, and sensitive POC assay detects SARS-CoV-2 and influenza A virus simultaneously (Photo courtesy of Sensors and Actuators B: Chemical, DOI:10.1016/j.snb.2024.136933)

To assess the diagnostic accuracy of the TDD system, 15 nasopharyngeal swabs each from healthy individuals, COVID-19 patients, and those with influenza A were tested. The results, published in Sensors and Actuators B: Chemical, showed that for COVID-19, the TDD system correctly identified positive samples in 93.3% of cases and negative samples in 96.7%. For influenza A, positive and negative samples were correctly identified in 100% and 96.7% of cases, respectively. This study highlights the TDD system as a promising novel diagnostic tool for accurate and rapid simultaneous detection of multiple viruses at the point of care, potentially enabling clinicians to make timely and informed treatment decisions.

"The application of our TDD system can be further expanded by introducing additional channels and sensing hydrogels on the microfluidic chip, as well as integrating highly sensitive nucleic acid amplification systems for simultaneous detection and differentiation of a wider range of viruses," said INU’s Professor Eunjung Kim who led the TDD’s development.