Saliva tests may be considered
an option for detecting SARSCoV-2 infection if gold / nasopharyngeal swabs cannot be obtained
, but should preferably be used within the first 5 days of onset of symptoms. This is indicated by the circular of the Ministry of Health on their use which dictates the indications on the collection of samples and on the reporting of cases. The test is indicated as useful for "repeat screenings" for professional or other reasons, on the elderly or disabled and on children in the school setting. Some studies have found sensitivities ranging from 53 to 73%.
The circular, reiterating that the molecular test on nasopharyngeal and oropharyngeal sample represents the international gold standard for the diagnosis of COVID-19 in terms of sensitivity and specificity,
indicates the obligation of traceability of all tests, including salivary ones, in information systems regional
.
The results of molecular tests on salivary samples, even if carried out by laboratories, structures and private professionals accredited by the Regions, must be included in the reference regional information system.
"The use of saliva for the diagnosis of SARS-CoV-2 infection involves a non-invasive collection method, however the correct collection of the salivary sample is a crucial step. Saliva samples can be heterogeneous (oral saliva, oropharyngeal saliva posterior) and the different techniques and collection sites may have an impact on the sensitivity of the method ", reads the circular.
Additionally, saliva samples can be mucous and viscous, resulting in processing difficulties with existing automated RNA extraction or extraction / amplification methods and equipment.
There are rapid antigen tests that have been validated in EU Member States on the basis of alternative samples, such as saliva, sputum and / or faeces, and it is questionable whether these tests should also be included in the list of rapid antigen tests agreed by the 'HSC. In addition, the sensitivity decreases after the first five days of the onset of symptoms. Overall, the available studies indicate a variable diagnostic sensitivity of molecular tests on saliva samples, in relation to the collection technique: a higher sensitivity was detected in the early morning posterior oropharyngeal saliva, while a lower sensitivity was observed with the technique. of "general spitting". (collection of saliva accumulated at the level of the oral floor).
