• Sat. Oct 16th, 2021

Salivary tests Covid, green light with limitations: when to use them


May 15, 2021

The Ministry of Health gives the green light to molecular salivary tests but with some limitations “because sensitivity decreases after the first 5 days from the onset of symptoms” and because “the saliva sample can be considered an option for the detection of Sars-CoV-2 infection if it is not possible to obtain gold / nasopharyngeal swabs “. This is what is foreseen in the new circular of the Ministry of Health, signed by the Director General of Prevention Gianni Rezza, on the use of molecular and antigenic tests on saliva for professional use for the diagnosis of Sars-CoV-2 infection. “The saliva sample can be considered an option for the detection of Sars-CoV-2 infection in asymptomatic individuals who are repeatedly screened for professional or other reasons, to increase the acceptability of repeat tests, in particular: if very elderly or disabled individuals are screened and if there is a shortage of tampons “, underlines the circular indicating when to use the molecular salivary test. In the circular on salivary tests, the ministry technicians highlight how “the use of saliva for the diagnosis of Sars-CoV-2 infection provides a non-invasive method of collection, however the correct collection of the salivary sample is a crucial step. The samples saliva can be heterogeneous (oral saliva, posterior oropharyngeal saliva) and the different techniques and collection sites can have an impact on the sensitivity of the method. In addition, the saliva samples can be mucous and viscous, causing difficulties in processing with the methods and existing automated RNA extraction or extraction / amplification equipment “. Furthermore, “saliva has been evaluated as a possible substrate for antigen tests based on automatic laboratory instrumentation, with chemiluminescence reading – concludes the circular – At the moment, the available repertoire of such Ce-Ivd labeled tests for the salivary matrix is ‚Äč‚Äčlimited. , but it is being expanded. Comparison with the molecular test indicates a sensitivity similar to that observed for the nasopharyngeal swab for saliva. Molecular salivary tests “can represent a useful tool for monitoring and controlling Sars-CoV-2 infection in the school setting. Some studies published in 2020 have found sensitivities between 53 and 73%” underlines the new circular of the Ministry of Health.