CORONAVIRUS – Covid-19 case tracing is not dead, it is evolving. Under fire from critics since the start of the health crisis, “tracing” is now given a prefix – “retro” – revealing a new ambition on the part of Health Insurance.
Generalized this summer according to a press release from the organization, the retro-tracing therefore promises a tracing of contaminations chains “Japanese-style”, a country ahead of epidemiological issues and the identification of contact cases. Zoom on the workings of this method, supposed to avoid a new wave.
“Retrotracing brings a new building block to the fight against the epidemic. It tightens a little more the meshes of the net put in place to trace the chains of contamination and stop them ”, declared in a press release Thomas Fatôme, general manager of the National Health Insurance Fund.
Identify the moments, places and events at the origin of the transmission
In experimentation since March 25 in Côte-d’Or and Loire-Atlantique, retro-tracing has already proven its worth. It makes it possible to “go up higher in the chains of contamination” than did its cousin the “tracing”, underlines the general director of the National Health Insurance Fund (Cnam) Thomas Fatôme.
The challenge is to identify, beyond the people that the Covid-19 patient has met, the times, places, events at the origin of the transmission of Covid-19 as well as all those who have been “ co-exhibited ”.
Until now, the objective of the tracing was to identify the contact cases of a person positive for Covid-19 by going back over a period of 48 hours for the symptomatic and 7 days for the asymptomatic.
Too slow, not exhaustive enough, this tracing has had some setbacks. It took an average of 8 days for the Health Insurance to call the contact cases. A delay that made the isolation of contact cases completely inoperative, since it had already seen a lot of people during their infectious phase of Covid-19.
This period has gradually been reduced to three days, thanks to the efforts of the investigators and to better use of this technique. “The scientific consensus tells us that this device is only valid and effective below a circulation threshold which corresponds to roughly 5,000 cases per day,” said Thomas Fatôme. However, this has been the case since last week in France.
Taking advantage of these favorable conditions to trace the interactions of the identified cases, the retro-tracing promises to go further, taking into account the 10 days preceding the identification of the disease, further explained Thomas Fatôme this Thursday, June 17. at a press conference.
“This more in-depth health survey”, as Pierre Rousseau, director general of the Loire-Atlantique CPAM, describes it, “will allow“ going to question the positive person on the reasons, elements or moments of contamination, more or less collective, which may have been the source of this contamination ”if it occurred outside the home.
Identify the “co-exhibits” and the clusters
The objective behind this interrogation is to flush out “co-exposed” who shared with the positive these events of contamination. With the aim of encouraging them to isolate themselves. On June 1, retro-tracing was effective in 17 departments, 43 others were included on June 15 and the device will be generalized throughout France on July 1.
Who will do this retro-tracing? As with so-called “classic” or “prospective” tracing, Health Insurance is in charge. But with “readjusted” questions, “more intrusive”, “since the only question does not consist in knowing which people one could have contaminated, but in which situation, in which place, at which time”, notes Pierre Rousseau.
According to the data obtained during the experiment, when the contamination occurred outside the home, 10% of people are able to identify their circumstance of contamination, “as many situations that the health insurance will be able to invest”.
And according to these same figures, to be consolidated at the national level, this identification makes it possible on average to flush out about fifteen people co-exposed (of which approximately 10% become positive).
In collaboration with the ARS
In some cases, the regional health agencies (ARS) will be able to take the lead. “Especially when the event found does not allow the Health Insurance to identify all people by name,” explains Jean-Baptiste Calcoen, director of the national tracing mission at the Cnam, citing sports competitions, cultural meetings, homes, hospitals …
They may also have to travel “to untie the tongues”, when the contamination took place during a prohibited event, or “without the parents being aware”, notes Pierre Rousseau.
According to Health Insurance, retro-tracing will also strengthen the search for variants. Going back so far in the chain of contamination could stop the clusters of variants in a given region, and thus slow down their spread throughout the territory.
The system should also make it possible to identify types of events and places that are more contaminating. “Probably that in a few weeks, we will be able to say if there is more risk of being contaminated by participating in such types of events or in such other”, according to Jean-Baptiste Calcoen.
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