The coronavirus present from November 2019 in France? This study suggests
Analysis of blood samples dating from before December 2019 showed the presence of antibodies to the new coronavirus.
CORONAVIRUS – The coronavirus responsible for Covid-19 could have circulated in France as early as November 2019, even before its official detection in China in December, according to a study which does not, however, provide a categorical response.
These results “suggest an earlier circulation of SARS-CoV-2 in Europe than has been reported,” write the authors of this work, published on February 6 in the European Journal of Epidemiology.
In recent months, researchers from different countries have ensured that cases had gone unnoticed long before December 2019 , without being able to provide definitive proof. This type of work is essentially based on analyzes of wastewater or a posteriori tests of blood samples. It is this last method that was used by French researchers.
They took as a starting point 9,144 blood samples from the large Constances cohort, launched in France in 2012 for various epidemiological monitoring work.
They performed serological tests on these samples to detect the presence of antibodies to SARS-CoV-2, signs of a past infection. 353 of them were positive.
A second analysis to avoid false positives
To limit the risk of having false positives, they carried out a second, more detailed analysis in order to detect the presence of neutralizing antibodies.
Finally, 44 samples were positive on both tests, including 7 dating from November 2019 and 3 from December 2019.
In addition to these analyzes, eleven of these people were questioned to see if they had presented signs suggestive of Covid-19 at the time of the sample.
Five said they “showed signs of viral respiratory illnesses and eight had been in close contact with people who exhibited such signs or reported risk situations for potential exposure to SARS-CoV-2,” according to the study. .
“In more than half of the cases, we are dealing with people who have traveled or who have been in contact with people who have been sick”, one of the researchers, Prof. Fabrice Carrat, explained to Le Monde on Wednesday. from the Pierre-Louis Institute for Epidemiology and Public Health (Inserm, Sorbonne University).
However, we cannot be 100% sure that these results were not biased by false positives, even if the researchers did their utmost to limit the risk.
This question is “the main problem”, they write, while deeming “unlikely that all (of the samples) are false positives”.
The question of the origin of the coronavirus is geopolitically sensitive.
China emphasized studies suggesting that Covid-19 appeared in late 2019 in other countries. But the mission sent by the WHO to try – in vain – to uncover the origins of Covid-19 ruled on Tuesday that these studies did not provide sufficient proof.