## 3 Results and Discussion
### Circulatory System  
As previously mentioned, blood serves as a viable specimen for COVID-19 diagnosis. Presently, only a limited number of studies indicate the detectability of viral RNA in plasma or serum samples from COVID-19 patients [12]. Conversely, some studies suggest that the current approach for viral RNA detection using oral swabs may not be optimal, as instances exist where the virus is present in anal swabs or blood, yielding negative results in oral swab tests [12; 16]. Additionally, in challenging situations such as comatose patients, obtaining an oropharyngeal or nasopharyngeal sample may be difficult, making blood collection a potential alternative [12]. It is noteworthy that despite the identification of \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**N Total. Saliva Positive**} & \multirow{2}{*}{**Sensitivity (Positive Agreement \%) and Notes**} & **Type of** & **Reference** \\  & & **Molecular Test** & **Reference** \\ \hline \multirow{4}{*}{5 samples. 5/5 positives} & 100\% positive agreement (first saliva in the morning & \multirow{4}{*}{RNA extraction + RT-qPCR} & \multirow{4}{*}{[2]} \\  & compared to NPSs). Exception was in children by days & & \\  & 8-10 after the onset of symptoms that were positive for & & \\  & SARS-CoV-2 in NPSs but not in saliva. & & \\ \hline \multirow{4}{*}{401 samples. 20/35 positives} & The virus was detected in 6.5\% (n/N=26/401) cases by swab and 7.0\% (n/N=28/401) by saliva. For saliva the & & \\  & sensitivity was 73.1\% (95\% CI 52.2–88.4\%), the specificity & & \\  & was 97.6\% (95\% CI 95.5–98.9\%), the positive predictive & & \\  & value was 67.9\% (95\% CI 51.5–80.8\%) and the negative & & \\  & predictive value was 98.1\% (95\% CI 96.5–99.0\%). & & \\ \hline \multirow{4}{*}{28 samples. 19/23 positives} & 82.61\% positive agreement. & \multirow{4}{*}{RNA extraction + RT-PCR} & \multirow{4}{*}{[56]} \\  & In 3 convalescent patients, the virus was detected in & & \\ \cline{1-1}  & saliva in opposition to NPSs, at 4 time points. & & \\ \hline \multirow{4}{*}{36 samples. 20/27 positives} & 86\% positive agreement. The values of PPA and NPA & & \\  & were 85.0\% and 28.6\%, respectively. Compared with & & \\  & NPSs, OPS, and sputum, saliva had higher detection & & \\  & performance and less false negatives. & & \\ \hline \multirow{4}{*}{432 samples. 46/53 positives} & 98.4\% positive agreement. & \multirow{4}{*}{RNA extraction + RT-PCR} & \multirow{4}{*}{[55]} \\  & Almost equal to or higher viral loads in saliva than in & & \\ \cline{1-1}  & NPSs/OPS (saliva 1.07 \(\pm\) 0.34–1.65 \(\pm\) 0.46 log10 & & \\ \cline{1-1}  & copies/mL, versus NPSs/OPS & & \\ \cline{1-1}  & 1.18 \(\pm\) 0.12–1.34 \(\pm\) 0.30 log10 copies/mL) & & \\ \hline \multirow{4}{*}{16 samples. 4/7 positives} & Detection of viral RNA in 7 out of 16 saliva specimens (43.8\%) and viral antigen in 4 out of 7 positive saliva specimens (47.8\%). & Rapid immunochromato- & \\ \cline{1-1}  & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._SARS-CoV-2 RNA in infected patients' plasma or serum, there is currently no evidence of SARS-CoV-2 transmission through blood transfusion [12]. In what concerns the risk of infection for the health professional, the blood tests have less harm than the tests where respiratory swaps are used [12] since the patient does not need to remove the mask. This fact justifies the score given to the Infection Risk for the Health Professional criteria (4.0). According to the WHO (2000), the material necessary for a blood sample collection includes a skin disinfection solution (70% alcohol or 10% povidence iodine), swabs, gauze pads, a band-aid, a tourniquet, a vacutainer, and a monovette or disposable syringes and needles and blood culture bottles. All the described material justifies the score of 3.0 in the criteria Materials and Equipment.