Ruidx Biosciences Secures FDA Emergency Use Authorization for Digital PCR-Based SARS-CoV-2 Detection Kit with Fully Integrated DropX-2000 System

On June 25 (U.S. time), RainSure Scientific’s FastPlex Triplex SARS-CoV-2 Detection Kit (RT-Digital PCR), used in conjunction with RainSure Scientific’s DropX-2000 series of fully enclosed, highly automated digital PCR systems, received Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration (FDA). Currently, the FDA has granted EUA for only three digital PCR-based SARS-CoV-2 tests worldwide. The other two EUA-approved digital PCR platforms are from well-known U.S. manufacturers. Both RainSure Scientific’s digital PCR instruments and its digital PCR-based SARS-CoV-2 detection kit were independently developed and have obtained FDA EUA approval.

To date, RainSure SCIENTIFIC’s COVID-19-related products have successively obtained EU CE-IVD certification, approval from the Indian Council of Medical Research (ICMR), and U.S. FDA Emergency Use Authorization (EUA), and have been included in the Chinese Ministry of Commerce’s export whitelist, laying a solid foundation for RainSure SCIENTIFIC’s expansion into the international market.

It is reported that RainSure SCIENTIFIC’s DropX-2000 digital PCR system features a fully enclosed chip design, preventing sample contact with the external environment and thereby avoiding aerosol contamination after amplification. The system employs a four-fluorescence-channel design, enabling simultaneous detection of the N gene, ORF1ab gene (commonly referred to as the O gene in some contexts), and human reference genes within a single well for COVID-19 testing. Furthermore, RainSure SCIENTIFIC utilized certified reference materials for SARS-CoV-2 from the National Institute of Metrology, China (NIM) for value traceability and quality control. The National Institute of Metrology conducted testing on RainSure’s digital PCR kits and instruments. Leveraging the unique high sensitivity and absolute quantification capabilities of digital PCR technology, the system provides robust evidence for COVID-19 screening, disease progression assessment, and discharge criteria evaluation.

In a research paper published by RainSure SCIENTIFIC in collaboration with Nantong Third People's Hospital on the four-color digital PCR system for monitoring treatment efficacy and discharge testing in COVID-19, the same kit was used to compare detection performance between digital PCR and qPCR platforms. The digital PCR platform achieved an accuracy rate of 96.3%, with the limit of detection improved by 1–2 orders of magnitude. The study identified a real-world case where a patient deemed ready for discharge based on clinical criteria still tested positive for trace amounts of viral residue via digital PCR, whereas qPCR failed to detect it. Such scenarios pose a risk of disease relapse and potential transmission to healthy individuals.

On May 22, 2020, a research paper by the team of Lan Ke and Chen Yu from the State Key Laboratory of Virology at Wuhan University was published in the journal Emerging Microbes & Infections. The study employed digital PCR to detect samples from various environmental sites, identifying SARS-CoV-2 in patients’ restrooms, rooms where healthcare workers changed their protective gear, and intensive care unit (ICU) rooms housing critically ill patients. These findings fully demonstrate the potential application of the high sensitivity of digital PCR in environmental monitoring. The study revealed that, compared with RT-PCR—the gold standard technology widely used in the nucleic acid testing industry—droplet digital PCR (ddPCR) offers more prominent advantages for the clinical detection of low viral loads of SARS-CoV-2, thereby reducing false-negative results. This discovery will serve as a strong complement to current nucleic acid testing standards.

Similarly, among nearly 50 environmental monitoring samples tested by the Jiangsu Provincial Center for Disease Control and Prevention in collaboration with RainSure SCIENTIFIC’s digital PCR platform, multiple weakly positive samples were identified, further corroborating the reliability of these findings.

Currently, RainSure Scientific’s COVID-19-related products are also being utilized at frontline anti-epidemic institutions such as Wuhan Huoshenshan Hospital and the National Institute of Metrology, China. Furthermore, beyond its applications in COVID-19 testing, digital PCR holds substantial potential for use in fields including liquid biopsy, companion diagnostics, and quality control.

Suzhou RainSure Scientific, established in 2017 and co-founded by several Ph.D. holders who studied in the United States, boasts profound academic expertise and extensive industrial experience. The company has built a comprehensive talent pipeline spanning mechanical kinematics, optics, microfluidics, imaging, chemistry, and biology. Adhering to the philosophy of “Global R&D, Intelligent Manufacturing in China,” RainSure Scientific is committed to innovation and intelligent manufacturing to advance public health, focusing on cutting-edge technological innovations and product development in the broader healthcare sector. Its product portfolio encompasses two main segments: digital PCR systems and microfluidic solutions. Current offerings include the DropX-1000 and DropX-2000 series digital PCR systems, the PG-MF Controller microfluidic flow controller, and more than 50 types of digital PCR assay kits for research use. RainSure Scientific’s products have been sold to over 40 enterprises and renowned universities in China and the United States, receiving widespread acclaim.

RainSure Scientific Equipment Platform