Molecular salivary swabs: how they work and when they will be useful for the green pass

Students from some sentinel schools will do them to monitor the spread of the infection. And, according to the version of the decreto green pass approved last week by the Chamber of Deputies, i salivary tests they will also be used to issue the green pass from 48 hours worth (but it is always essential to get vaccinated). It will be necessary to understand if the Senate, as probable given the times, will confirm that provision that is useful in particular for children over two years of age, who must present the green pass but cannot get vaccinated, because it is less invasive than the tampons we have been used to up to today (rapid or molecular antigenic substances differs little in terms of taking the sample to be analyzed, always from the nose or throat).

But what exactly are salivary tests and how do they work? The saliva sample can also be subjected to molecular analysis O antigenica, therefore, in the first case looking for portions of Rna of the virus or, in the second, for specific proteins of the envelope. In short, just like for the swab that picks up the mucus, also for the one that picks up the saliva there can be two paths.

The use is regulated by a circular from the Ministry of Health now of last May, even if this type of tampons did not take off in a particular way during the summer. In that document, the ministry seemed to want to reduce its use to those cases in which the classic oropharyngeal sampling was not available and preferably as confirmation of the infection within the first five days of the onset of symptoms. But with the provisions approved by the Chamber, that recommendation will skip and salivary swabs, just as it will be done in schools, will become the second type of withdrawal possible to obtain a certificate of negativity and therefore the green pass after the oropharyngeal one.

The tampon, usually some kind of lollipop which should be kept in the mouth for a few minutes (you must be fasting, not having smoked, brushed your teeth, drunk, used chewing gum and preferably in the morning), collects a small amount of saliva and checks for the presence of portions of the RNA of the virus or, in case of antigenic investigation, of Sars-CoV-2 surface proteins. In the second case, the result arrives in about ten minutes and any positivity must be confirmed with a further examination, an unnecessary step with a PCR test, considered the golden standard. But the withdrawals that the boys will make, and those that will give access to the green pass, are the ones who will be subjected to molecular analysis, which must necessarily be processed in the laboratory and the results of which are usually available after 24 hours. We talked about it here with Valentina Massa, Professor of Applied Biology at the State University of Milan.

Salivary antigenic tests, of which there are also do-it-yourself versions as well as oropharyngeal ones on the other hand, they are not and will obviously not be useful to obtain the green pass but only as a personal and precautionary screening.