Assessment of the Diagnostic Ability of Four Detection Methods Using Three Sample Types of COVID-19 Patients

• Published in: Frontiers in cellular and infection microbiology 2021-06, Vol.11, p.685640-685640
• Main Authors: Yu, Fei, Xie, Guoliang, Zheng, Shufa, Han, Dongsheng, Bao, Jiaqi, Zhang, Dan, Feng, Baihuan, Wang, Qi, Zou, Qianda, Wang, Ruonan, Yang, Xianzhi, Chen, Weizhen, Lou, Bin, Chen, Yu
• Format: Article
• Language: English
• Subjects: Cellular and Infection Microbiology; COVID-19; COVID-19 - diagnosis; COVID-19 Nucleic Acid Testing; COVID-19 Testing - methods; dd-RT-PCR; Humans; Nasopharynx; Pandemics; RNA, Viral - genetics; RT-RAA; Saliva; sample type; SARS-CoV-2; Specimen Handling
• ISSN: 2235-2988; 2235-2988
• DOI: 10.3389/fcimb.2021.685640

Viral nucleic acid detection is considered the gold standard for the diagnosis of coronavirus disease 2019 (COVID-19), which is caused by SARS-CoV-2 infection. However, unsuitable sample types and laboratory detection kits/methods lead to misdiagnosis, which delays the prevention and control of the pandemic. We compared four nucleic acid detection methods [two kinds of reverse transcription polymerase chain reactions (RT-PCR A: ORF1ab and N testing; RT-PCRB: only ORF1ab testing), reverse transcription recombinase aided amplification (RT-RAA) and droplet digital RT-PCR (dd-RT-PCR)] using 404 samples of 72 hospitalized COVID-19 patients, including oropharyngeal swab (OPS), nasopharyngeal swabs (NPS) and saliva after deep cough, to evaluate the best sample type and method for SARS-CoV-2 detection. Among the four methods, dd-RT-PCR exhibited the highest positivity rate (93.0%), followed by RT-PCR B (91.2%) and RT-RAA (91.2%), while the positivity rate of RT-PCR A was only 71.9%. The viral load in OPS [24.90 copies/test (IQR 15.58-129.85)] was significantly lower than that in saliva [292.30 copies/test (IQR 20.20-8628.55)] and NPS [274.40 copies/test (IQR 33.10-2836.45)]. In addition, if OPS samples were tested alone by RT-PCR A, only 21.4% of the COVID-19 patients would be considered positive. The accuracy of all methods reached nearly 100% when saliva and NPS samples from the same patient were tested simultaneously. SARS-CoV-2 nucleic acid detection methods should be fully evaluated before use. High-positivity rate methods such as RT-RAA and dd-RT-PCR should be considered when possible. Furthermore, saliva after deep cough and NPS can greatly improve the accuracy of the diagnosis, and testing OPS alone is not recommended.