France is expanding its testing policy. Since Saturday July 11 and until October 30, pharmacies have been authorized to carry out rapid diagnostic orientation tests (TROD) to find out if a person has been in contact with the coronavirus. Until now reserved for medical analysis laboratories, these tests make it possible to know, in a few minutes, whether one has developed, or is in the process of developing, an immune response.

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A drop of blood is taken from the skin, usually at the tip of the finger, and then it is brought into contact with a reagent. If the result is positive, it should be confirmed in a biology laboratory by a blood test and an examination in order to clarify the reality of the immune response. A virological test (RT-PCR) can also be performed to check whether the virus is still present in the body and thus avoid contagion situations.

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A list of 51 authorized rapid tests has been published by the Ministry of Health. Some only detect IgG antibodies (for immunoglobulin G), which form at least 14 days after contact with the virus. Others also indicate the presence of IgM (immunoglobulin M), produced earlier and which can be detected about a week after infection.

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Pharmacists had been asking for many weeks to be able to market these TROD tests, while the unions of medical biologists were firmly opposed to it. In a press release dated July 3, several biologist organizations put “Warns the authorities and the general public about the difficulties of use and the complexity of interpreting the results of rapid diagnostic orientation tests. “


Three types of screening tests

Les tests PCR. They consist of taking nasal cells using a swab, a long cotton swab, inserted into the nostrils. Until now, this method has been the most reliable in case of symptoms.

Serological tests. They must make it possible to detect antibodies in the blood of a patient and therefore to determine if he has already contracted the coronavirus in the past. There are 139 of them on the market, according to the health ministry, but not all of them have been found to be reliable.

Saliva tests. Developed in Montpellier, their effectiveness would be very close to the PCR method, but much faster and less unpleasant than nasal swabs.