We have "a very large arsenal in France for serological tests," said Professor Dominique Le Guludec, president of the French National Authority for Health (HAS) when delivering her opinion on rapid tests on May 18. These allow you to know, from a drop of blood taken at your fingertip, whether a person has encountered the virus; they can be performed in a medical analysis laboratory or in pharmacies in particular. "We are now awaiting the decree from the Ministry of Health which will validate the usable tests and their administration in pharmacies", specifies Emmanuel Lataste, president of the network of Elsie Health pharmacies. HAS, on the other hand, warns against self-tests, carried out alone by the patient at home, because there is a difficulty in interpreting the results. These tests are not as easy to "read" as a pregnancy test.
There are 4 types of serological tests, specifies the HAS in a "memo sheet" attached to its opinion. On the one hand, the automated tests, carried out from a blood test in a city or hospital laboratory, which delivers the results in a few hours; they measure the quantity of different types of antibodies. On the other hand, the so-called unit tests, carried out from a simple drop of blood taken at the fingertip; they simply detect whether a given amount of antibody is present and are divided into three categories: RDTs (rapid diagnostic tests) are done in the laboratory by a biologist; TRODs (rapid diagnostic orientation tests) are done in a doctor's office or pharmacy; Finally, the self-tests are sold in pharmacies but can be done anywhere by the patient himself.
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The experts took their time to deliver their recommendations in order to avoid the fiasco in Spain where a poor serological test had been used. But despite two initial opinions on serological tests, including a report on May 2 on the so-called "Elisa" tests (carried out in the laboratory by a blood test), the Ministry of Health is slow to deliver the list of authorized tests. In early May, the Directorate General of Health had claimed that the CNR (National Center for Respiratory Infections, located in Lyon and Paris) had not yet made its assessments on the first tests. Which was incorrect.
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A more complete list is now expected, which should be supplemented by the “quick” test marks. She will arrive "very soon," assured the president of HAS on May 18. Why have the Ministry of Health and the ANSM (National Medicines Agency) not yet published the list of approved tests, the reliability of which has been verified by the CNR? However, it is necessary to allow reimbursement of tests prescribed by prescription. No test, even the immuno-diagnostic tests (by blood test) of Roche and Abbott, already deployed in medical analysis laboratories, has been formally authorized by the French authorities. Many doctors were however awaiting this list for May 11 and deconfinement in order to complete the diagnosis of “negative” patients on the virological test (by PCR). As for medical laboratories, they have already started to carry them out. In fact, many tests can already be marketed legally across the European Union, as regulations allow companies to self-certify their tests.
Millions of people affected
Of "millions of people are concerned" , in France, by serological tests, said the owner of the HAS. These serological tests all provide a more or less precise indication of the body's production of antibodies after infection with Sars-CoV-2; a family of tests (the TROD) must be rechecked in the event of a positive result. However, the presence of antibodies does not indicate, in the current state of scientific knowledge, whether a person is immunized and for how long.
The tests are reliable two weeks after the onset of symptoms. In its specifications of April 16, HAS indicated that they must have a specificity greater than 98% (that is to say, they limit the number of “false positives” to 2%) and be sensitive at least 90% (for epidemiological studies only) or at least 95% to limit the number of "false negatives".