Comparing SARS-CoV-2 Viral Load in Human Saliva to Oropharyngeal Swabs, Nasopharyngeal Swabs, and Sputum: A Systematic Review and Meta-Analysis

Table 6

Study characteristics of SARS-CoV-2 viral load in saliva indicated by copies/mL RNA.

Author	Reference	Study design	Viral load in saliva (copies/mL RNA)	SD and IQR	Method to detect viral load	Saliva sample source	% SARS-CoV-2 positive	Total cohort size	Days onset	Symptomatic	Asymptomatic
Barclay (2020)	[51]	Experimental study	1 × 10^4	SD: 0.07	RT-PCR	Patient-pooled saliva purchased from BioIVT (saliva-1902492)	35	49 diagnostic remnant samples	NA	ND	ND
			CT value: 28.15
Kim (2020)	[52]	Cross-sectional	Mean log10: 3.98 (9550 copies/mL RNA)	SD: 0.90	RT-PCR	NR	100	7	0–13	NR	NR
Ning (2021)	[53]	Experimental study	5.65 × 10^7	SD: 2.28 × 10^4	RT-qPCR and CRISPR-FDS	NR	43	103	1–7	NR	NR
To (2020)	[54]	Cross-sectional	Median: 3.3 × 10^6	IQR: 9.9 × 10^2–1.2 × 10^8	RT-qPCR	Cough out saliva from the throat into a sterile container	91.7	12	0–7	NR	NR
			Mean: 4.5 × 10^7	SD: 1.02 × 10^8

All median values, if present, are original and obtained from the publication. Authors were contacted for the original dataset. NR = not reported, NA = not applicable, ND = not detected, NPS = nasopharyngeal swab, OPS = oropharyngeal swab, SD = standard deviation, and IQR = interquartile range.