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. 2020 Nov 1;12(21):20997-21003.
doi: 10.18632/aging.104020. Epub 2020 Nov 1.

Evaluation of droplet digital PCR for quantification of SARS-CoV-2 Virus in discharged COVID-19 patients

Chong Liu  1 , Qingxin Shi  1 , Mingfei Peng  1 , Ruyue Lu  1 , Haohao Li  1 , Yingying Cai  1 , Jiaxi Chen  1 , Jiaqin Xu  1 , Bo Shen  1
Affiliations

Evaluation of droplet digital PCR for quantification of SARS-CoV-2 Virus in discharged COVID-19 patients

Chong Liu et al. Aging (Albany NY). .

Abstract

The worldwide severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has led to the rapid spread of coronavirus disease (COVID-19). The quantitative real time PCR (qPCR) is widely used as the gold standard for clinical detection of SARS-CoV-2. However, more and more infected patients are relapsing after discharge, which suggests qPCR may fail to detect the virus in some cases. In this study, we selected 74 clinical samples from 43 recovering inpatients for qPCR and Droplet Digital PCR (ddPCR) synchronous blind detection, and established a cutoff value for ddPCR diagnosis of COVID-19. The results showed that at a cutoff value of 0.04 copies/μL, the ddPCR sensitivity and specificity are 97.6% and 100%, respectively. In addition, we also analyzed 18 retained samples from 9 discharged patients who relapsed. Although qPCR showed all 18 samples to be negative, ddPCR showed 12 to be positive, and there was only one patient with two negative samples; the other eight patients had at least one positive sample. These results indicate that ddPCR could significantly improve the accuracy of COVID-19 diagnosis, especially for discharged patients with a low viral load, and help to reduce misdiagnosis during recovery.

Keywords: COVID-19; SARS-CoV-2; discharged criteria; droplet digital PCR.

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Conflict of interest statement

CONFLICTS OF INTEREST: The authors declare that they have no conflicts of interest that could have appeared to influence the work reported in this paper.

Figures

Figure 1
Figure 1
The ROC curve for ddPCR.
Figure 2
Figure 2
Flow diagram of the study population.
See this image and copyright information in PMC

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