Self-tests have passed by the million every week since the end of December.
Massive use which will probably increase further with the new health protocol in schools and the foreseeable progression of contact cases.
But their reliability depends on how they are made.
Much more than champagne or the galette des rois, self-tests are the fashionable product at the start of this year loaded with coronavirus.
Quick and can be stored for use at home, unlike antigenic or PCR tests (only available in screening centers, hospitals or pharmacies), self-tests sell like hot cakes.
However, this massive use is not without questions for this month of January.
20 Minutes
takes stock.
Are the self-tests reliable?
Of the three types of test offered - PCR, antigen and self-test - these are the least reliable, immediately warns Sébastien Hantz, professor of virology at the University of Limoges.
The PCR has a “benchmark efficiency, even if it does pass some false negatives.
For an antigen, the reliability is considered to be around 80% ”, notes the expert.
What about the self-test? Studies are difficult to carry out on this, as it also depends on the way in which the sample is taken. However, the self-test being done alone, and not with a health professional, "it is almost impossible to know concretely the number of false negatives that it lets through", continues Sébastien Hantz. Especially since the sample is highly unpleasant: it requires inserting a swab 2 to 3 centimeters deep into the nostril, which can cause pain. This can lead to the temptation not to insert it far into the nostril, resulting in reduced effectiveness. In addition, for a nasopharyngeal PCR test, the rod is inserted much deeper into the nose and allows more virus to be collected. One thing is certain therefore, even with a perfect method,"The self-test remains the least reliable test", concludes the virologist.
“It's better than nothing, but you have to keep in mind that you can absolutely be negative with him and positive for the coronavirus.
We can therefore have a lot of false negatives wandering around with a false sense of security, ”worries the virologist.
Will there be sufficient stocks of self-tests?
During Christmas week, 58% of pharmacies were out of stock, said the spokesperson for the Union of Pharmacy Pharmacists Unions Gilles Bonnefond to our JDD colleagues.
The Minister of Health, Olivier Véran, mentioned six million self-tests carried out the days before Christmas, almost as much as the number of antigen and PCR tests over the same period: 7.3 million.
Pierre-Olivier Variot, president of the Union des Syndicats de Pharmaciens d'Officine, expects an even massive demand over the next few days: "At least for this week, until the effect of December 31 ends and the case contacts of the evenings are tested. Then it's more unpredictable. "
But the demand could last even longer. According to epidemiologist Arnaud Fontanet, the peak of cases could take place in mid-January. Even more cases are therefore to come in the coming days - France is already at 160,000 daily cases on average over the past week - or even more contact cases and therefore even more tests. "We expect to sell three million self-tests per week by January 15," confirms Philippe Besset, president of the Federation of Pharmaceutical Syndicates of France, against about half as much in the previous week.
All the unions contacted are unanimous: "normally", the stock should follow, because large orders have been placed in anticipation.
"Provided, however, that the large distribution does not buy all the stocks", specifies Pierre-Olivier Variot.
In addition to pharmacies, supermarkets can sell self-tests until January 31, to facilitate their purchase.
And with the new school protocol?
Philippe Besset recognizes it: this calculation of three million weekly self-tests dated before the new health protocol in schools, decreed this Sunday by the Minister of Education, Jean-Michel Blanquer.
From this Monday, all children in a class with a positive case must perform a PCR or antigen test, as was already the case, but also two others on D + 2 and D + 4, offered free of charge in pharmacies .
“It could create tensions, especially in the first week.
Afterwards, we should know how to adapt, ”hopes Philippe Besset.
Pierre-Olivier Variot also wants to be reassuring: “Pharmacists are ready and if stocks follow, which the government has promised, there should be no worries.
Our profession will respond present, as always.
"
Society
Coronavirus: Isolation, tests for schoolchildren, teleworking ... Everything that changes this Monday
Health
Coronavirus: The sale of self-tests authorized outside pharmacies until January 31
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epidemic
Covid 19
Coronavirus
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