Saliva sample tests may be more effective at detecting omicrons, according to a new study published in the medical journal “MedRxiv,” which was released by the media earlier in the week. Results not yet confirmed. For Moud Mrabbet, coordinator of the National Center for Public Health Emergency Operations, such a study is encouraging and is closely monitored by Moroccan authorities.

How can we better detect omicrons that are actively moving around and causing large numbers of infections? This question is answered by a new study published in the medical journal “MedRxiv” and relayed by the “New York Times.” It appears from earlier results, which have not yet been confirmed and validated by peers, that omicrons are more easily observed through saliva tests, rather than PCR or antigen tests, which are delta’s Would be more useful to find out. , The authors of this preliminary study point out that the effectiveness of the tests used depends on the type of test we are working with. “If for Delta, a PCR test in the nose was more effective than a saliva test (100% versus 71%), then for Omicron it is the opposite (86% versus 100%),” the study said.

What do Moroccan scientists think of these new findings?

Asked about this, Maud Marabet, coordinator of the National Center for Public Health Emergency Operations at the ministry, told the newspaper “Le Matin” that “saliva tests are currently used in Morocco as a means of detecting Sars-CoV-2 infection.” The results of international studies on the performance of these tests with respect to the Omicron variant are encouraging, and to add that the “Technical and Scientific Committee is concerned with various aspects of the strategy to fight against COVID-19 at the international level.” but closely follows all scientific data: tests, treatments, etc. Recommendations to this effect are issued regularly by the said committee.”

For Jafar Heikel, professor of epidemiology and specialist in infectious diseases, “the current study, as cited above, is showing us that there is a breakaway in terms of screening compared to the new Omicron strain”. Furthermore, he concedes, “with this type of prevalence the ability of current tests to detect is questioned”. And the professor recalls that PCR tests, nasopharyngeal tests or saliva samples are used to test for COVID-19, not to identify the variant. “Obviously, we can have more false negatives, no matter what type they are. Already PCR, for classic strain, alpha, delta, omicron, type of sample, when and how it is done, and quality And there was a significant percentage of false negatives depending on the area of ​​the sample.”, specifies PR Heikel. In statistics, he testifies, “with classic PCR we can have up to 30% of false negatives. A percentage that can increase in some situations with Omicron”. With regard to saliva or nasopharyngeal tests, the infectious disease specialist provides some details. “You have to be careful with these tests by taking into account 4 parameters: the sensitivity of the test, its specificity, its positive predictive value and its negative predictive value. The critical elements that will allow us to know to what extent a sample able to detect true positive or true negative”.

Still according to our interlocutor, the clinical side, today, is one of the important methods that have proven their worth to detect Covid-19 and its variants: “At the level of our team, we have clinical “There is a scale of measures that allows confirmation by PCR tests to be more oriented toward delta or omicron”. He summarizes his observations that screening alone remains insufficient, with CT and biology of the lungs It also plays a role in the detection and control of disease.