COVID-19.With Omicron, following the contact cases is it useful to combat the epidemic?

Who, in this month of January 2022 marked by the emergence of the Omicron variant, has not been in contact?With up to 500,000 new daily cases, the number of people who inherited this uncomfortable status has also exploded.

Insofar as all of France seems to be in contact or be doomed to become it soon, this concept and the crisis management tools attached to it still have meaning and utility?Response elements.

At first, was the Tracing contact ...

Since the start of the pandemic, the contact case concept has been intimately linked to its operational exploitation: contact Tracing.

This process aims to go up and break the contamination channels by identifying the people who have been in contact with a positive case and asking them to isolate themselves or test themselves

Read also: Podcast.At the heart of a TRACING contact cell

Led by health insurance teams, these operations were supposed to allow, according to the expression devoted, to "keep control of the epidemic".What they never really allowed to do.

"During peaks, this principle of following contacts could not be 100 % effective because there were too many contacts to follow," sums up Jean-François Gehanno, university professor and member of the High Council of Public Health.

"In France, we know that contact Tracing is effective up to 5,000/10,000 cases a day," said Jonathan Roux, epidemiologist at the School of Advanced Public Health Studies.

A method impossible to follow with omicron

We will have suspected, this process has become impossible to apply to the time of an omicron variant responsible for hundreds of thousands of cases every day.

In an opinion on the issue, published in early January, the High Council for Public Health already provided for it: with Omicron, "the number of daily contaminations will be quickly greater than 200,000 new cases and, in fact, the number of contacts will be considerable, making impossible the measures of quarantine ”set up for contact cases.An all the more true observation, at present, where the number of daily cases fluctuates between 400,000 and 500,000.

READ ALSO: COVID-19.The 500,000 contamination bar in 24 hours crossed for the first time

"500,000 cases per day, if we multiply by the number of contacts, that makes at least one million and a half people to contact", counts Jonathan Roux.A challenge.In fact, in the field "all contact cases are not called as we did before," recently explained to Ouest-France Mohamed Azgag, the director of the Primary Health Insurance Fund of Morbihan.

Read also: Why are COVID patients are no longer called by health insurance

In addition to the profusion of cases it causes, the speed with which Omicron contaminates its victims makes these Tracing Contacts operations even more ineffective."With historical variants, the median incubation time before the appearance of symptoms was six days.For the omicron variant, it is three days.And as we know that people are contaminants 24 to 48 hours before developing symptoms, it is certain that it makes the device very complicated and probably quite ineffective, "sums up Jean-François Gehanno.In short, "we are overwhelmed by omicron kinetics", notes the professor of the Rouen University Hospital.

A device to redirect

Nevertheless, the definition of the contact cases of a positive person, and the ensuing tracing, could keep some use.

In what case, precisely?If the device "towards people who need a specific management," said Jonathan Roux.Or "people not vaccinated, fragile people, immunocompromised people ..."

"If the contact case is someone at risk of serious forms, there is the possibility of prescribing a treatment," abounds Jean-François Gehanno.This is where the anti-Cavid pills designed by Pfizer and other Mercks would come into play.

Health insurance teams therefore always have a decisive role to play, for the most sensitive cases.

Mass tracing contact has become informal

For the rest of the population, more informal tracing remains in force: that which, since the start of the pandemic, has been organized on the job within the population,

"We saw that there was a bit of a change in the population," notes Jonathan Roux.Now people are contacting the people they have seen in the last 48 hours to tell them that they are in contact with.And often, they do it with great precaution, considering that some people may be in contact when they are not according to the rules which were enacted by health insurance ".

If, according to the researcher, these prejudices were able to contribute to clogging the test system at the beginning of January, they are nonetheless a good thing to help stem the epidemic, or at least slow down its progress."It's a good way to get around the circuit and alert your contacts more quickly," agrees Jean-François Gehanno.

The difficulty of changing rules

But, for these cases contacts alerted by the unofficial circuits, there remains a difficulty: to be there.Because the recommendations, more and more precise and changing, have what to mislead the most assiduous."We must adapt the protocol to the virus we are facing," recalls Jonathan Roux.But to change our strategy too much, we lose the population who no longer knows which test to use and when ".

And Jean-François Géhanno to summarize the problem, in a formula with the undeniable scientificity: "I note the rapid evolution of scientific knowledge, I therefore understand the necessary evolution of recommendations and regulations.And I unfortunately see that it makes pedagogy complicated.»».A theorem that can apply to many facets of the pandemic.