Where do we get the most contamination? This is the question to which theComCor study¹ of the Institut Pasteur, led by epidemiologist Arnaud Fontanet, is trying to respond. The preliminary results of the study were revealed by Europe1 December 17th. They show that contaminations mainly take place at home, but also in bars and restaurants.

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Meals in a private or public setting

The Scientific Council has already cited this study in its December 12 note and presented the main conclusions: “The ComCor study carried out in France last October-November on the places and circumstances of new infections shows the high risk of transmission of the virus during meals, whether they take place in private (family, friendly) or public (cafes , restaurants …) ” It is on these results that the government has relied to issue its recommendations and justify the restrictive measures taken at the end of the year.

Bars, restaurants and sports halls

In detail, a first section concerns 3,400 people contaminated by covid and 1,700 uncontaminated in October and November. A comparison of these two groups shows that frequenting restaurants, bars or sports halls was associated with an increased risk, unlike public transport or shops (food, clothing, etc.).

But “you should be careful“in the interpretation of these results, insists Arnaud Fontanet to AFP. The study was indeed carried out in October / November, during the curfew and then the re-containment, when the establishments were partially or even completely closed. is therefore difficult to know “what is the real share of restaurants and bars in the transmission“virus.

“Clandestine” contamination?

According to the study, the risk increases even more during confinement than during curfew. “This suggests that there were bars and restaurants open clandestinely during the lockdown“and that the people who went there, even fewer,”exposed themselves a lot“, suggests Professor Fontanet.

The majority of home infections

In a second part, the study analyzed the circumstances of contamination based on data from 25,600 infected people drawn from the health insurance files and interviewed by questionnaire. This section shows that the place most conducive to contamination is the home, generally via the spouse for two thirds of the contaminations.

In particular, “meals play a central role in these contaminations, whether in a family, friendly or less professional environment“, since we are close to each other, and without a mask.

“Private gatherings – families, friends – are the main source of infection“, reminds AFP Professor Fontanet.”If people have friendly dinners at their homes rather than going to a restaurant, that doesn’t change a thing. “

Only 42% of contaminated people isolated early enough

Thus, according to this study, the two main risk situations are meals, then proximity to children.

But another contaminating situation is the delay in isolation. And if 97% of patients isolated themselves, only 42% did so from the first symptoms, without waiting to be tested. However, the first five days of the disease are the most contaminating, reported a recent British study.

Salespeople, workers, health workers …

Finally, the study suggests that the professions most affected by covid are salespeople, health workers, administrative executives, workers and drivers.

The study will be continued in the coming months to refine these initial results and to learn more about the transmission of the virus in other spaces, such as places of culture.

“It is not a censorship tool to say “Be careful, this is where it happens”, but on the contrary a tool that will accompany reopening to see if we detect an excess risk.“, concludes Professor Fontanet.

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¹Study of socio-demographic, behavioral and practical factors associated with a risk of infection with SARS-CoV-2