Rapid and simultaneous visual screening of SARS-CoV-2 and influenza virufses with customized isothermal amplification integrated lateral flow strip.

Due to the similar clinical symptoms of influenza (Flu) and coronavirus disease 2019 (COVID-19), there is a looming infection threat of concurrent Flu viruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this work, we introduce a customized isothermal amplification integrated lateral flow strip (LFS) that is capable performing duplex reverse transcription-recombinase polymerase amplification (RT-RPA) and colorimetric LFS in a sequential manner. With customized amplification primer sets targeted to SARS-CoV-2 (opening reading frame 1a/b and nucleoprotein genes) and Flu viruses (Flu A and Flu B), the platform allows the rapid and simultaneous visual screening of SARS-CoV-2 and Flu viruses (Flu A and Flu B) without cross reactivity, false positives, and false negatives. Moreover, it maximally eases the detection, reduces the detection time (1 h), and improves the assay performance to detect as low as 10 copies of the viral RNA. Its clinical application is powerfully demonstrated with 100% accuracy for evaluating 15 SARS-CoV-2-positive clinical samples, 10 Flu viruses-positive clinical samples, and 5 negative clinical samples, which were pre-confirmed by standard qRT-PCR. We envision this portable device can meet the increasing need of online monitoring the serious infectious diseases that substantially affects health care systems worldwide.