Digital PCR assay for the effective detection of COVID-19 patients with SARS-CoV-2 low viral load
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Updated: Nov 4, 2025
Two-Step Reverse Transcription Droplet Digital PCR Protocols for SARS-CoV-2 Detection and Quantification
Published on: March 31, 2021
Yong Sun1, Chengchao Ding2, Qingqing Chen1
1Anhui Center for Disease Control and Prevention, Hefei, Anhui, 230601, China; Key Laboratory for Medical and Health of the 13th Five-Year Plan, 12560, Fanhua Avenue, Hefei, Anhui, China.
Objective:
Viral nucleic acid detection by real-time reverse transcription polymerase chain reaction (qPCR) is the current standard method for diagnosis of SARS-CoV-2 infection. However, due to low viral load in some COVID-19 patients, false negative results from this method have been repeatedly reported.
Method:
In this study, we compared the sensitivity and specificity of digital PCR (dPCR) in simulated samples and clinical samples with qPCR assay through a series of vigorous tests.
Results:
The results showed that dPCR was more sensitive than qPCR especially for samples with low viral load (≤3 copies). In addition, dPCR had similar specificity as qPCR and could effectively distinguish other human coronaviruses and influenza virus from SARS-CoV-2. More importantly, dPCR was more sensitive than qPCR in detecting the virus in the "negative" samples from recurrent COVID-19 patients.
Conclusions:
In summary, dPCR could serve as a powerful complement to the current qPCR method for SARS-CoV-2 detection, especially for the samples with extremely low viral load, such as recurrent COVID-19 patients.
