Table A.2.
Studies that directly compared saliva use in SARS-CoV-2 detection with respiratory samples and that demonstrated inaccurate saliva results. Natal/RN, 2020.
| Authors | Study design | Study population | Sample size [Gender] | Age range [Mean] (Years) | Test | Saliva type | Saliva collection method | Respiratory sample | Results |
|---|---|---|---|---|---|---|---|---|---|
| Jamal et al., 202035 | Cohort study | Positive patients for COVID-19 with nasopharyngeal, midturbinate or nasal swab. | 91 [52 M, 39 F] | 23-106 [66] | RT-PCR | Saliva | Self-collection by spit. | NPS | 72 patients had at least one positive specimen (nasopharyngeal swab or saliva). 61% of these 72 patients, both were positive, 28% only the nasopharyngeal swab was positive, and in 11% only saliva was positive. Nasopharyngeal swabs were 17% more sensitive than saliva overall. |
| Fang et al., 202036 | Cohort study | COVID-19 patients admitted to Central Hospital of Xiangtan. | 32 [16 M, 16 F] | 34-54 [41] | RT-PCR | – | – | Nasal swab. | Nasal swab samples showed 100.0% positivity, while the positive rate for saliva was 78.1%. The viral shedding time of SARS-CoV-2 of nasal swab was significantly longer than that of blood and saliva. |
| Kim et al., 202037 | Cohort study | Patients with SARS-CoV-2 infection. | 15 [5 M, 10 F] | 17-91 [59] | rRT-PCR | Saliva | Self-collection by spit. | NPS/OPS and sputum. | General rRT-PCR sensitivity for saliva compared to the sensitivity for naso/oropharyngeal samples was lower, being 64% and 77% respectively. |
| Chong et al., 202038 | Cohort study | COVID-19-infected children. | 18 [10 M, 8 F] | 1,8–11,1 [6,6] | rRT-PCR | Saliva | Self-collection by spit or through syringe. | NPS | The Ct values had statistically significant differences between saliva and NPS samples (1–3, 4–7 and 8–10 days after onset symptoms), and did not differ significantly in the period of 11–15 days. In five children, saliva samples tested negative on day 1–3 and became positive on day 4–7. |
| Williams et al., 202039 | Cross-sectional study | Outpatients who come to a COVID-19 screening clinic. | 622 [-] | – | RT-PCR | Saliva | Self-collection by spit. | NPS | 39 positive tests for SARS-CoV-2 by nasopharyngeal swab (33 tested positive for saliva). Nucleic acid was detected in the saliva from 1 out of 50 patients with negative test for nasopharyngeal swab. |
| Kam et al., 202040 | Cross-sectional study | Pediatric hospitalized patients confirmed for COVID-19. | 11 [-] | Symptomatic 2,1–12,5 [4,8] Asymptomatic 0,3–11,8 [3,8] |
RT-qPCR | Saliva | Oral swab. | NPS | SARS-CoV-2 was detected in at least 1 oral swab sample in 9 of the 11 children (81.8%). Two children with positive nasopharyngeal tests had negative results in the saliva samples in two collection days. In general, oral samples produced lower viral loads and had low sensitivity (25–71.4%) compared to nasopharyngeal samples. |
| Skolimowska et al., 202041 | Cross-sectional study | Symptomatic healthcare workers and household contacts presenting to a COVID-19 outpatient clinic. | 132 [43 M, 89 F] | 30-51 [39] | RT-PCR | Saliva | Saliva without cough. | NPS/OPS | Among the paired samples, 18 NP/OP swab samples tested positive, with 15 tested positive also for saliva. Saliva obtained sensitivity and specificity of 83.3% and 99.1%, respectively. Saliva Ct values were significantly higher than for swabs. |
| Lai et al., 202042 | Cross-sectional study | Patients with SARS-CoV-2 infection confirmed. | 50 [23 M, 27 F] | 16-72 [-] | RT-PCR | Saliva | Clearing the throat gargling saliva. | NPS and throat swab and sputum. | Saliva samples obtained RT-PCR positivity lower rates (68.7%) and lower viral RNA concentrations (mean log copy/mL 3.54) compared to sputum (89.4%, 5.03) and swabs (80.4%, 4.63). |
| Landry et al., 202043 | Cross-sectional study | COVID-19 suspected symptomatic outpatients. | – | – | RT-PCR | Saliva | Saliva without cough. | NPS | Among the 35 positive samples, 33 were positive for NPS, while 30 were positive for saliva. The general sensitivity for saliva was 85.7% (95% CI 70.6%–93.7%). The median Ct value was significantly lower for NPS than for saliva (p = 0.0331). |
NPS: Nasopharyngeal swab; OPS: Oropharyngeal swab; RT-PCR: Reverse Transcription Polymerase Chain Reaction; rRT-PCR: Real-time Reverse Transcription Polymerase Chain Reaction; RT-qPCR: Quantitative Reverse Transcription Polymerase Chain Reaction.