Covid-19: a study reveals the fluctuating effectiveness of self-tests

RQuick and practical, the self-tests were particularly popular during the holidays, marked by records of Covid contamination. In France, due to demand “unprecedented since the start of the health crisis”, the government now authorizes their sale in supermarkets until January 31, to “diversify the supply and sales channels for self-tests” . But it should be done correctly and be careful with their outcome. According to a comparative study by the Paul-Ehrlich Medical Institute, the Robert-Koch Institute and the Charité Hospital in Berlin, reported by our colleagues from BFMTV, their reliability is variable.

Thus, the sensitivity rate of certain tests was found to be insufficient to “correctly detect” cases of Covid-19. This concerns 26 tests out of 122 carried out. The others met all the criteria, some even showing very good results. The study estimates that the sensitivity rate of the self-tests ranges from 30% to 100%.

A PCR test for confirmation

The good students are the self-tests of the Guangdong Longsee laboratory and that of the Lifecosm Bitech laboratory which achieve a sensitivity of 100%. Those from the Citest Diagnostics laboratory reach 98% and are among the best, as are those from the French laboratory Toda Pharma (86% sensitivity).

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The study also reveals a fluctuating effectiveness of the self-tests according to the moment of the infection of the contaminated patient. Thus, they prove to be particularly reliable 5 to 7 days after the onset of symptoms, when the viral load is at its maximum. Like antigenic tests, self-tests are therefore less reliable than laboratory PCR tests, which are still recommended to confirm a result, according to the authors of the study.

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