Table I.
Main characteristics of included articles
| Reference | Country, year | Study design | No. of patients | Sex | Mean age (years) | Saliva collection method | Saliva sample preservation | SARS-CoV-2 detection method | Sensitivity (%) for saliva | Specificity (%) for saliva | Viral load in saliva (copies per mL or Ct) | Viral load in NPS (copies per mL or Ct) | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | To et al.12 | Hong Kong, China, February 2020 | CS | 12 | 7 M 5 W |
62.5 | Spit | VTM | RT-qPCR | – | – | 3.3 × 106 copies/mL (range, 9.9 × 102 to 1.2 × 108 copies/mL) | – |
| 2 | Zheng et al.17 | China, February 2020 | CS | 65 | 40 M 25 W |
54 | Coughing up and spitting | – | RT-qPCR | – | – | – | – |
| 3 | To et al.18 | Hong Kong, China, March 2020 | CS | 23 | 13 M 10 W |
62 | Coughed up | VTM | RT-qPCR | – | – | 2 log10 copies per mL to 6 log10 copies per mL | 5 × 2 log10 copies per mL (IQR, 4.1-7.0) |
| 4 | Azzi et al.19 | Italy, April 2020 | CS | 25 | 17 M 8 W |
61.5 | Drooling and pipetting | PBS (2 mL) | RT-qPCR | – | – | Ct 27.16 ± 3.07† | – |
| 5 | Azzi et al.20 | Italy, April 2020 | CR | 2 | 2 M | 67.5 | Drooling and pipetting | PBS (2 mL) | RT-qPCR | – | – | – | – |
| 6 | Williams et al.13 | Australia, April 2020 | CS | 522 | – | – | Spit | Liquid Amies media | RT-qPCR | 84.62% | 98% | – | – |
| 7 | Wyllie et al.21 | USA, April 2020 | CS | 44 | 23 M 21 W |
61 | Self-collected saliva and spit | – | RT-qPCR | – | – | – | – |
| 8 | Pasomsub et al.11 | Thailand, May 2020 | CS | 19 | 9 M 10 W |
33 | – | UTM | RT-qPCR | 84.21% | 98.9% | ORF1 ab gene Ct 32.7 (28-35.0) N gen Ct 31.8 (28.4-33.7)* | ORF1 ab gene Ct 32.0 (27.434.3) N gen Ct 30.5 (26.1-32.3)* |
| 9 | Yoon et al.14 | South Korea, May 2020 | CR | 2 | 2 W | 55.5 | – | VTM (2 mL) | RT-qPCR | – | – | Patient 1 = 6.63 log10 copies/mL Patient 2 = 7.10 log10 copies/mL | Patient 1: 8.41 log10 copies/mL Patient 2 = 7.49 log10 copies/mL |
| 10 | McCormick-Baw et al.22 | USA, May 2020 | CS | 156 | 90 M 66 W |
47.8 | – | Unpreserved | RT-qPCR | 95.92% | 99.06% | E gene Ct 26.10 ± 11.20; N2 gene Ct 30.40 ± 9.67† |
E gene Ct 23.83 ± 7.78; N2 gene Ct 26.70 ± 7.61† |
| 11 | Becker et al.23 | USA, May 2020 | CS | 112 | – | – | Self-collected and spit | Oragene·Dx Kit | RT-qPCR | 40%-60% 20%-50% |
97%-100% 75%-94% |
– | – |
| 12 | Iwasaki. et al.24 | Japan, June 2020 | CS | 76 | – | 69 | Self-collected saliva and spit | PBS (600 μL) | RT-qPCR | 88.89% | 98.51% | 4.1 ± 1.4 log10 gene copies/mL Ct 30.6 ± 4.6† |
5.4 ± 2.4 log10 gene copies/mL Ct 26.5 ± 8.1† |
| 13 | Hung et al.25 | Hong Kong, China, June 2020 | CS | 18 | 8 M 10 W |
39.1 | Coughed up | VTM (2 mL) | RT-qPCR | – | – | Early morning Ct 34.5 (32.5-41); before lunch Ct 38.2 (33.9-41); before teatime Ct 36.3 (34.5-41); before dinner Ct 41 (34.7-41); before bedtime Ct 41 (34.7-41)* | Ct on admission 28.09 (17.71-36.6)* |
| 14 | Chen et al.26 | Hong Kong, China, June 2020 | CS | 58 | 28 M 30 W |
38 | Coughing up followed by spit. | VTM (2 mL) | RT-qPCR | 89% | 66% | E gene Ct 29.7 (27.2-37.2); N2 gene Ct 32.3 (29.9-38.6)* | E gene Ct 26.8 (20.7-33.5); N2 gene Ct 29.3 (23.3-36.5)* |
| 15 | Jamal et al.27 | Canada, June 2020 | CS | 91 | 52 M 39 W |
66 | Spit | PBS (2.5 mL) | RT-qPCR | 68.75% | 70.37% | Ct 34.0 (31-37)* | Ct 30.0 (26-35)* |
| 16 | Nagura-Ikeda et al.28 | Japan, July 2020 | CS | 103 | 66 M 37 W |
– | Self-collected and spit | – | RT-qPCR RT-LAMP |
81.6% | – | – | – |
| 17 | Migueres et al.29 | France, August 2020 | CS | 123 | 49 M 74 W |
43 | Spit | – | RT-qPCR | 82.93% | 96.34% | RDrP gene Ct 29.5 (27.6-33.3)* |
RDrP gene Ct 24.9 (21.9-30.9)* |
| 18 | Kim et al.30 | South Korea, August 2020 | CS | 15 | 5 M 10 W |
59 | Spit | UTM | RT-qPCR | 64% | – | Ct 32.0 (28-38)* | Ct 33.0 (27-35)* |
| 19 | Caulley et al.31 | Canada, August 2020 | Mass screening | 1939 | – | – | Self-collected and spit | OMNIgene·ORAL, OM- 505 (DNA Genotek) |
RT-qPCR | 60.71% | 99.26% | – | – |
| 20 | Yokota et al.32 | Japan, September 2020 | Mass screening study | 1924 | 981 M 858 W 95 unknown |
Cohort 1: 44.9 Cohort 2: 33.5 | – | None | RT-qPCR RT-LAMP |
92% | >99.9% | – | – |
| 21 | Sakanashi et al.33 | Japan, September 2020 | CS | 12 | – | – | Self-collected (drooling) | VTM (3 mL) | RT-qPCR | 79% | 69% | – | – |
| 22 | Mestdagh et al.34 | Belgium, October 2020 | Mass screening | 2289 | – | – | Spit and saliva swab | Norgen Biotek's Saliva RNA Collection and Preservation Device Dx 53800 | RT-qPCR | 30.8% overall (spit) 22.4% Overall (swab) 97% in high viral load samples (spit) 76.7% in high viral load samples (swab) | – | – | – |
CR, case report; CS, Case-series; IQR, interquartile range; M, men; n, number of included patients, considers patients with PCR SARS-CoV-2 diagnosis; PBS, phosphate-buffered saline; RT-LAMP, reverse transcription loop-mediated isothermal amplification; RT-PCR, reverse transcription polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; UTM, universal transport medium; VTM, viral transport medium; W, women.
⁎
Median (IQR).
†
Mean ± standard deviation.