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Covid-19: the “Breton variant”, an overestimated danger?  – Covid-19: this Breton variant more difficult to detect


Three weeks later his placement under surveillance by health authorities, the new variant of Sars-CoV-2 detected in Lannion is far from having delivered all its mysteries. Only 26 cases have been officially confirmed, including the most recent, this Thursday, at the Guingamp hospital center. A patient. Like everyone else, a chain of transmission has been established with the Lannion hospital where the first case, a patient there too, arrived in mid-January. He nevertheless we had to wait until the end of February for the alert to be given and that the “Breton variant” be formally identified, ten days later, thanks to the sequencing carried out at the Institut Pasteur. Only three cases have been detected outside Brittany, in Paris, Nantes and another in Mayenne, now hospitalized in Fougères, all linked to Lannion.

National surveillance measures

To date, 12 patients have died from it. Frail, elderly and / or people with co-morbidities. However, it is impossible to conclude that there is a higher mortality caused by this variant compared to the others. The problem lies in the difficulty of detecting this mutant which often nestles deep in the respiratory system, rendering conventional nasopharyngeal PCR tests negative. “We have a surveillance bias. We have the results where we are able to find the virus. That is to say in the hospital, in people intubated in intensive care, for whom we can perform effective deep samples, ”explains Alain Le Tertre, head of the Brittany unit of Public Health France.

How many people are circulating with the virus? Surveillance measures have been extended to all of France by the Directorate General of Health, March 30, to identify any patient with specific clinical, biological and epidemiological pictures. “Investigations carried out on cases defined as probable outside Brittany have all turned out to be false leads”, observes Alain Le Tertre. National surveillance has also been activated in hospitals.

“General practitioners see the Breton variant everywhere”

The media impact of the case has put doctors on the alert. Perhaps a little too much according to this expert working on the file: “General practitioners see the Breton variant everywhere and ask for research on the stool, for patients who have just had fever and diarrhea for ten days. There is a case definition to follow and it is not! “.

This lack of propagation at the national level What was the support for the fifth flash survey?, reassures scientists. And irritates some others, in front of “the abnormal extent” taken by the subject. “It became an emergency, when we were perhaps just dealing with a variant in a cluster that would not broadcast more. And, indeed, that seems to be the case, “blows this same source.

On the side of Public Health France, we are not lowering our guard, in the face of new cases which appear sporadically in hospitals in Trégor: “The virus must be there. There are surely other cases in nature but as it is difficult to detect, that complicates things, ”notes Alain Le Tertre. With his team, he examines epidemiological indicators, such as the proportion of negative symptomatic tests. “For the moment, none of them allows us to suppose that there is a wide distribution of this variant which would supplant the others. But it can circulate at low noise. As we have seen with the British variant, it took a while for it to gain the upper hand. “

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