The EasyCov saliva test promises easy, painless Covid-19 screening in just an hour. - Sylvain THOMAS / AFP

  • A Montpellier consortium has invented a rapid saliva test that is much less invasive than screening by PCR.
  • This device gives a positive or negative result for Covid-19 in one hour.
  • Still in the testing phase, if this device is validated by the health authorities, it would represent a valuable tool in the government's massive screening strategy for the coronavirus.

A few drops of saliva and a result in barely an hour: the Covid-19 saliva screening tests are strongly expected. Especially since today, in the heart of summer, almost everyone wants to be tested to find out if they are carrying the coronavirus. Before going on vacation, directly to your holiday resort, or near your home, especially when a cluster has been unearthed there: it's the rush for screening centers. We still have to find a free niche.

In Paris as in the rest of France, the screening centers are saturated. If the lack of qualified personnel to perform PCR screening was already chronic since the start of the Covid-19 epidemic, with the summer holidays, the explosion in the demand for tests and the departure on vacation of many biologists, it is the traffic jam! So, how do you ensure the massive screening promised by the government? What if the solution came from EasyCov saliva tests? Developed by a Montpellier start-up attached to the National Center for Scientific Research (CNRS), this device would make it possible to tell in less than an hour whether a patient is positive or not for the coronavirus, simply by means of a saliva sample under language. Problem: They are still not available on the market. "We are at war against the virus and you tell us that we must still wait, it is not possible", would have stormed Olivier Véran on July 22, putting pressure on the Public Assistance of Paris Hospitals (AP- HP) to advance the schmilblick. Why ? Are they as effective as PCR tests? Are they reliable anyway?

"Simplify screening and reduce waiting times"

If saliva tests are also expected, it is because they represent a major stake in the massive screening strategy. If they prove to be effective, they could constitute an alternative to screening by nasopharyngeal swab. Because if the gesture seems simple at first glance, sticking a swab in the nostril of a patient requires a know-how for which it is necessary to have been trained. “You have to push the swab deep enough to take where the virus is lodged, for about ten seconds, and in each nostril. It is a rather unpleasant sample to undergo for the patient, not to mention that today, we lack professionals trained to carry out these tests, ”explains 20 Minutes  Dr. François Blanchecotte, president of the Union of biologists.

"We are asking for the simplification of screening tests," continues the biologist, "with faster and just as reliable samples, to increase our capacities and be able to ensure massive screening. We asked the Minister of Health two weeks ago if we could perform screening by saliva sample, but we have not received a response. And despite the pressure he put on the AP-HP to speed up the process, there is still no return, and the saliva tests remain on stand-by ”.

Ensure the reliability of tests

Because before resorting to it in all directions, it is necessary to ensure the reliability of these saliva tests. However, they leave some doctors skeptical. "These tests are not reliable", judged Professor Jean-François Delfraissy, even if he thinks that they will evolve and that "by the end of August", we will be able to have them. But “this test is already on the market, it is used in certain airports, thanks to the very rapid results it provides,” adds François Blanchecotte. The problem is the loss of sensitivity of the test when done through the saliva. To this day, there are still a lot of false negatives, around 34%, and that's a problem. The saliva tests would be less sensitive, the virus could be less present in the saliva, therefore more difficult to detect. However, the objective is precisely to identify those who are carriers of the virus, hence the importance of carrying out comparative studies to ensure the reliability of this device ”.

Thus, a meta-analysis published at the end of May, carried out on samples taken from patients whose Covid-19 infection had been previously confirmed, showed that the nasopharyngeal samples have a detection sensitivity of 98%, against 91% for saliva samples. But “saliva tests are a promising alternative to nasopharyngeal swabs for the diagnosis of Covid-19. (…) However, more research is needed before introducing saliva samples more systematically in the diagnoses of SARS-CoV-2 ”, declared the authors of this meta-analysis.

This is why "the government has asked for additional results on the experiments underway at the Montpellier University Hospital," says one on the communication side of INOVIE, the laboratory which produces and will distribute EasCov. We are awaiting the latest results, but we have already obtained the CE mark for this device ”. So, in practice, when will these saliva tests be available? The Directorate General of Health (DGS) ensures that "the validation of the performance of saliva tests is underway by the French Society of Microbiology", as the "finalization of the protocol". But this is only an intermediate step. Then it will be necessary to wait for the High Authority of Health to examine and validate them "within a short period of time given the stakes", adds the DGS, without advancing a date. "We are now awaiting the last results of these saliva tests, and to see if they will be validated by the National Reference Center (CNR) for respiratory viruses at the Institut Pasteur, which validated the other screening tests today. authorized, says Prof. Blanchecotte. This would give the green light to resort to it massively, perhaps even in self-sampling ”.

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  • Covid 19
  • epidemic
  • Screening
  • Health
  • Coronavirus