## 3 Results and Discussion
### Digestive System
Since it also can be self-collected [2; 6; 56] and there is no need for trained personnel to perform it, the risks for the healthcare professionals are reduced [6], as is the amount of personal protective equipment needed [54]. This means that the use of saliva specimens for diagnosis of COVID-19 implies a reduction in the risk for both the professional healthcare and patients [57]. This justifies the score 5.0 attributed to Specialized RH criteria, Infection Risk for the Health Professional criteria, and Infection Risk for the Patient criteria. Thus, saliva has many advantages compared to NPSs and OPS sampling including a decrease in risk to healthcare professionals, a reduction in patient discomfort, and no requirements for specialized materials [53]. There is also no need for trained healthcare workers or personal protective equipment [6; 53]. Another advantage is that saliva can provide a larger amount of test material than upper respiratory swabs [52]. Additionally, several reports indicated that SARS-CoV-2 was detected in saliva specimens of equally or higher sensitivity than the NPSs [57] and that the sensitivity to detect SARS-CoV-2 using saliva is high, as demonstrated in Table 3. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**N Total. Saliva Positive** & **Sensitivity (Positive Agreement \%) and Notes** &
\begin{tabular}{c} **Type of** \\ **Molecular Test** \\ \end{tabular} & **Reference** \\ \hline \multirow{6}{*}{74 samples.} & \multicolumn{3}{c}{91.37\% positive agreement.} \\  & The CT value for detection of the SARS-CoV-2 ORF1 & \\  & gene tendentially lower in saliva than that of NPSs & \\  & (mean 27.07; 95\% CI, 25.62 to 28.52 vs. mean 28.24; 95\% CI, 26.62 to 29.85, although & \\ \cline{1-1}  & statistically (\(p>0.05\)). & \\ \hline \multirow{6}{*}{522 samples.} & \multicolumn{3}{c}{91.37\% positive agreement.} \\  & The CT value for detection of the SARS-CoV-2 ORF1 & \\ \cline{1-1}  & gene tendentially lower in saliva than that of NPSs & \\ \cline{1-1}  & (mean 27.07; 95\% CI, 25.62 to 28.52 vs. mean 28.24; 95\% CI, 26.62 to 29.85, although & \\ \cline{1-1}  & statistically (\(p>0.05\)). & \\ \hline \multirow{6}{*}{522 samples.} & \multicolumn{3}{c}{84.6\% positive agreement (33/39 patients, 95\% CI} \\  & 70.0–93.1%) in opposition to NPSs than only had & \\ \cline{1-1}  & \(39/522\) SARS-CoV-2 positive cases & \\ \cline{1-1}  & (6.3\%; 95\% CI 4.6–8.5\%). The median CT value was & \\ \cline{1-1}  & lower in NPSs compared with saliva and was correlated & \\ \cline{1-1}  & with the days from symptom onset in both samples. & \\ \hline \multirow{2}{*}{166 samples.} & \multicolumn{3}{c}{93.75\% positive agreement using ddPCR (15 out of} \\  & 16 samples) and 100\% using RT-qPCR (16 out of} & \\ \cline{1-1}  & and ddPCR & \\ \hline \multirow{2}{*}{459 samples.} & \multicolumn{3}{c}{81.1\% positive agreement, and 90.0\% in samples with} \\  & moderate to high viral load. The mean CT values were & \\ \cline{1-1}  & on higher in saliva compared with NPSs. & \\ \hline \multirow{2}{*}{31 samples.} & \multirow{2}{*}{23.08\% positive agreement and 75\% positive agreement} & \multirow{2}{*}{RT-qPCR} & \multirow{2}{*}{[51]} \\  & critically ill patients & \\ \hline \multirow{2}{*}{58 samples.} & \multirow{2}{*}{84.5\% positive agreement.} & Xpert Xpress & \\ \cline{1-1}  & & SARS-CoV-2 assay & \\ \hline \multirow{6}{*}{185 samples.} & \multicolumn{3}{c}{16.22\% positive agreement.} \\ \cline{1-1}  & The mean viral load was 5677 \(\pm\) 13,647 compared to & \\ \cline{1-1}  & \(16\),224 \(\pm\) 67,507 at NPSs. & \\ \cline{1-1}  & Many patients in the recovery period negative for & \\ \cline{1-1}  & SARS-CoV-2 in NPSs were positive with other & \\ \cline{1-1}  & specimens, particularly in anal swabs. & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Sensitivity obtained at detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) using saliva. CI: confidence interval. COVID-19: Coronavirus Disease 2019. CT: cycle threshold. ddPCR: droplet digital PCR. NM: not mentioned.