In the midst of a coronavirus epidemic, several thousand diagnostic tests can be performed every day in laboratories, even in the city since March 8.
Principle: what does the coronavirus diagnostic test consist of?
The diagnostic test consists of a nasopharyngeal sample (throat, nose, nasopharynx) which is done using a small swab (brush). It must be carried out by a doctor or a nurse.
The sample is then analyzed by a specialized laboratory to search for the presence of the genetic material of the coronavirus and thus confirm the diagnosis of the infection. It is a test that is not invasive and is easy to perform. “Initially, this test was only carried out in reference centers because they had the researchers and all the necessary technologies.
Now, most of the large hospitals are equipped with it so that they can give a quicker response in the event of suspicion of coronavirus infection. In the end, most laboratories will be able to practice them too, but for this type of epidemic, this will stay at hospital level for a long time, “comments Marie-Francoise Gros.
Who can take this test? And when ?
Not tested who wants. It is not because we have symptoms similar to those caused by the coronavirus that we will be able to benefit from a diagnostic test. Especially since we are in an epidemic of flu and many other viruses that can manifest in the same way are currently circulating.
At this stage of the epidemic, the protocol defined on the government site explains that “the test is carried out only in the event of suspicion of the disease, validated by the SAMU and a referent infectiologist”.
In other words, several criteria must be met to be considered a suspect case: in addition to the presence of clinical signs such as:
1- cough,
2-fever and especially
3-respiratory distress,
Those eligible for a screening test are those who return from a risk zone or have been in close contact with a person detected positive.
In the areas where the virus is very active, if the cases become very numerous, the ARS have the possibility of waiving the obligation of systematic screening.
Only patients with severe clinical conditions and residents of medico-social establishments with symptoms then remain subject to a test in these territories.
“It must be understood that the tests are useful for understanding where the virus circulates, they become less essential in the areas of active circulation where it is the medical care which becomes central” justifies the government on its site.
Results deadline
The time to get a result is between three and five hours.
What is the diagnostic test for?
Detecting the coronavirus through a diagnostic test is essential to limit its spread. Several types of coronavirus are capable of causing respiratory infections whose manifestations range from a simple cold to respiratory distress.
“In the most severe cases, a biological sample will make it possible to identify the responsible pathogen. In addition, the realization of a scanner or an X-ray of the lungs makes it possible to evaluate the extent of the pulmonary lesions and to determine the care of the person, “says the specialist.
Two new coronavirus tests
In the current context of public health emergency, bioMérieux, specialist in diagnostic solutions, is currently developing two tests to detect the SARS-Cov-2 virus, responsible for the Covid-19 epidemic. Because if its ranges currently on the market can detect other respiratory infections and other types of coronavirus, they are not able to detect the new virus.
“The first is a real-time PCR test that can test a hundred patients at a time. It is a test that can be performed in any laboratory using PCR techniques. It provides a result in 3 or 4 hours, which should be available before the end of March 2020.
Another fully automated test is being developed in parallel, which can be used for the individual diagnosis of an emergency patient. The advantage of this system is that always from a respiratory sample, you can get a result in 1 hour with a fully automated system. It is developed in our research centers in the United States, in partnership with the United States Department of Defense with which we have already worked for other tests “, details Marie-Francoise Gros.