The coronavirus was already present in France in the fall of 2019. This is what a study published on February 6, 2021 in theEuropean Journal of Epidemiology. The Parisian and Marseille researchers who signed this publication reveal that SARS-CoV-2 did not arrive in France at the end of January 2020, but that it was already circulating on French soil in November 2019.

Over 9,000 blood samples analyzed

Previous studies had put the chip in their ears. Analysis a posteriori chest scans performed at Albert Schweitzer hospital in Colmar (Alsace) had already shown probable cases of covid-19 in this department as of November 16, 2019.

Likewise, blood samples taken in the Avicenne hospitals in Bobigny and Jean Verdier in Bondy indicated the possible presence of the virus from December 2019 in Seine-Saint-Denis.

For this new, larger study, the researchers collected 9,144 blood samples collected from adults from the Constances cohort.¹ in France. The samples took place between November 4, 2019 and March 16, 2020, in 12 different regions.

13 positive samples before January 2020

The researchers carried out a test to detect antibodies against SARS-CoV-2, the immunoglobulins. In case of doubt, this test was confirmed by a test detecting neutralizing antibodies directed against the coronavirus.

Of all the samples, 353 showed positive serology at the time of collection. However, 13 of these samples had been collected between November 2019 and January 2020, that is to say before the official arrival of the coronavirus on the territory.

Travel, symptoms or contact case

11 of these participants responded to an additional questionnaire, which validated these results. Most of them had a consistent history of infection: either they had developed symptoms attributable to covid the week before the sample, or they had been in contact with someone who had such symptoms, or they were caregivers, or they had traveled shortly before the sample.

A case of reinfection?

And one of the participants in particular caught the attention of researchers. The serological test carried out on his blood sample from November 2019 was positive. Tested again in July 2020, he then had no neutralizing antibodies.

And in September 2020, he performed a PCR test following symptoms suggestive of covid. Test which turns out to be positive and which could therefore testify to a “possible reinfection“, note the researchers.

To confirm the possibility of reinfection in less than a year, but also to draw up a precise history of the arrival of the virus in France, it is now necessary to analyze more samples taken before November 2019.

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¹ Epidemiological cohort launched in 2012 in France with more than 200,000 participants.