Viral Load Kinetics of SARS-CoV-2 Infection in Saliva in Korean Patients: a Prospective Multi-center Comparative Study

• DOI: 10.3346/jkms.2020.35.e287
• Publication Date: 2020-08-06T06:54:25Z
• Authors: Seong Eun Kim; Ji Yeon Lee; Ahrang Lee; Soosung Kim; Kyung-Hwa Park; Sook-In Jung; Seung-Ji Kang; Tae Hoon Oh; Uh Jin Kim; Seung Yeob Lee; Seung-Jung Kee; Hee-Chang Jang
• Keywords: Adult; Aged, 80 and over; Male; 0301 basic medicine; Adolescent; SARS-CoV-2; Pneumonia, Viral; COVID-19; Middle Aged; Real-Time Polymerase Chain Reaction; 3. Good health; Betacoronavirus; 03 medical and health sciences; Nasopharynx; Republic of Korea; Humans; RNA, Viral; Original Article; Female; Prospective Studies; Coronavirus Infections; Saliva; Pandemics; Aged

This study was performed to compare the viral load and kinetics of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in saliva with those in standard nasopharyngeal/oropharyngeal (NP/OP) swabs.Fifteen patients with SARS-CoV-2 infection from four hospitals were prospectively enrolled and matched samples of nasopharyngeal/oropharyngeal swabs and saliva were collected at Day 1 of admission and every other day till consequently negative for two times. Real-time reverse transcription polymerase chain reaction (rRT-PCR) was performed to detect the envelope (E) and RNA-dependent RNA polymerase (RdRP) genes.The cycle threshold values of saliva were comparable to those of NP/OP swabs overall (P = 0.720, Mann-Whitney U test). However, the overall sensitivity of rRT-PCR using saliva was 64% (34/53), which is lower than the 77% (41/53) using NP/OP swabs. The sensitivity of rRT-PCR using saliva was especially lower in early stage of symptom onset (1-5 days; 8/15; 53%) and in patients who did not have sputum (12/22; 55%).Saliva sample itself is not appropriate for initial diagnosis of coronavirus disease 2019 (COVID-19) to replace NP/OP swabs, especially for the person who does not produce sputum. COVID-19 cannot be excluded when the test using saliva is negative, and it is necessary to retest using NP/OP swabs.