In two studies published online ahead of peer review, researchers in China have reported that the QX200 droplet digital PCR (ddPCR) system from Bio-Rad Laboratories, Hercules, Calif,  showed superior sensitivity and precision for clinical detection of SARS-CoV-2, the virus that causes covid-19, compared to existing test methods performed using qPCR.

Norman Schwartz, Bio-Rad.

Norman Schwartz, Bio-Rad Laboratories.

In the first study, clinicians in Wuhan, China, observed that a subset of infected individuals who tested negative for covid-19 using qPCR tested positive using ddPCR.1 The findings suggest that ddPCR can reduce false-negative results for covid-19 without any increase to false-positive results and could be a powerful complement to the current standard of testing.

The second study, led by the National Institute of Metrology and provincial Centers for Disease Control in China, concluded that droplet digital PCR significantly improves diagnostic detection accuracy for SARS-CoV-2 from 28.2% to 87.4%, thereby reducing false negatives.2 Furthermore, the researchers found that ddPCR is more sensitive and suitable for low viral load specimens from patients under isolation and observation even without any clinical symptoms.

“Bio-Rad is working to make ddPCR-based tests available for covid-19 detection and is partnering with Biodesix in Colorado to bring an emergency use authorization test online,” says Norman Schwartz, president and chief executive officer at Bio-Rad. “By more quickly identifying those who test positive for the virus, individuals can be quarantined and receive treatment as quickly as possible, helping to contain the spread of covid-19.”


1. Suo T, Liu X, Guo M, et al. ddPCR: a more sensitive and accurate tool for SARS-CoV-2 detection in low viral load specimens. MedRxiv. Epub March 6, 2020; doi: 10.1101/2020.02.29.20029439.

2. Dong L, Zhou J, Niu C, et al. Highly accurate and sensitive diagnostic detection of SARS-CoV-2 by digital PCR. MedRxiv. Epub March 30, 2020; doi: 10.1101/2020.03.14.20036129.