SARS-CoV-2 detection using digital PCR for COVID-19 diagnosis, treatment monitoring and criteria for discharge

Renfei Lu; Jian Wang; Min Li; Yaqi Wang; Jia Dong; Weihua Cai

The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10. 1101 Patient 9 first showed symptoms of fever, coughing and muscle pains on Feb. 4 th , 2020 and then 191 hospitalized on Feb. 13 th , 2020. However, pharyngeal swabs were negative by 14 th to Feb. 25 th for all 6 RT-PCR tests performed. CT results showed infection of both lungs. 193 However, due to the negative RT-PCR results, the patient was categorized as a suspected case despite 194 her positive CT results and symptoms. Although dPCR showed negative result on Feb. 14 th , the day 195 after the patient intake, low SARS-CoV-2 viral load (ORF1ab gene concentration of 0.34 copies/µl and 196 N gene of 0.43 copies/µl) was reported for the sample from Feb. 18 th . The negative results of February 197 14 th were most likely due to insufficient sample loading. The concentration of internal reference gene 198 was only 1.892 copies/μl, indicating low RNA load in the test. One Feb. 18 th , dPCR test result was 199 positive with the internal reference gene concentration at 20.8 copies/μl. It also suggested that the Feb. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.