Saliva as an Alternative Specimen for Molecular COVID-19 Testing in Community Settings and Population-Based Screening

Figures & data

Table 1 Profile of Patients with SARS-CoV-2 RT-PCR Positive Finding

	SARS-CoV-2 RT-PCR Positive (N=35)
	Swab+ Saliva Positive* (n=19)	Swab Only Positive* (n=7)	Saliva Only Positive* (n=9)
Age (years), mean ± SD**	30.6 ± 12.1	35 ± 8.6	32.1 ± 5.7
Male, n (%)	13 (68.4)	6 (85.7)	9 (100)
BMI, mean ± SD	24.9 ± 3.5	25.4 ± 4.2	26.6 ± 4.2
Smoker, n	2	Nil	1
Has co-morbidity,^# n	1	2	2
Symptomatic at presentation, n (%)	11 (57.9)	3 (42.8)	6 (66.7)
Duration of symptoms prior to the test (days), median (IQR)	2 (2–4)	2 (0)	4 (2–9)
Reported symptoms at presentation, n (%)
Fever (self-reported)	11 (57.9)	1 (14.2)	Nil
Cough	3 (15.7)	2 (28.5)	2 (22.2)
Sore throat	7 (36.8)	2 (28.5)	3 (33.3)
Shortness of breath	2 (10.5)	Nil	Nil
Muscle pain	6 (31.6)	Nil	Nil
Anosmia	2 (10.5)	Nil	Nil
Loss of taste	Nil	2 (28.5)	Nil
Vital signs
Body temperature (^oC), mean ± SD	36.9 ± 0.5	36.9 ± 0.6	36.4 ± 0.3
Body temperature ≥37.5°C, n	3	1	Nil
Oxygen saturation, mean ± SD	99.0 ± 0.8	98.8 ± 0.8	99.2 ± 1.3
Risk factor
Close contact with confirmed COVID-19 patient, n (%)	11 (57.9)	7 (100.0)	6 (66.6)
Travel history, n (%)	Nil	Nil	1 (11.1)

Notes: *Based on SARS-CoV-2 RT-PCR positive; **Not statistically different across groups; ^#Hypertension and diabetes.

Table 2 Viral Detection in Saliva and Swab Specimens

SARS-CoV-2 RT-PCR (N=401)		Swab
		Detected	Not Detected
Saliva	Detected	19	9
	Not detected	7	366

Figure 1 SARS-CoV-2 RT-PCR cycle threshold (Ct) values for the target genes in patients with paired positive samples (i.e. both swab and saliva samples positive).

Notes: (A) Ct values for RdRp gene in the swab and saliva of patients with paired positive samples. (B) Ct values for N gene in the swab and saliva of patients with paired positive samples.

Figure 2 Comparison of RT-PCR cycle threshold (Ct) in paired positive swab and saliva versus samples with only one specimen type positive.

Notes: (A) Ct values for RdRp and N genes in saliva: saliva positive/swab positive samples had significantly lower Ct values compared to saliva only positive samples. (B) Ct values for RdRp and N genes in swab: swab positive/saliva positive samples had significantly lower Ct values compared to swab only positive samples.