According to a study by researchers at the American University of Princeton published in the journal "Science" on Monday, the good weather will not harm the coronavirus pandemic.

Summer warming alone will not save the northern hemisphere from the Covid-19 pandemic, researchers at Princeton University in the United States concluded in a study published Monday by the journal Science .

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Negligible correlation

Statistical studies, conducted in recent months despite little progress on the new coronavirus, have established a slight correlation between the climate and the epidemic: the warmer and more humid it is, the less the virus will spread. However, these calculations remain preliminary and the biological link between climate and Sars-Cov-2, the virus that causes Covid-19, is fundamentally ignored. The models published in Science do not contradict the correlation, but consider it negligible for the moment.

"We anticipate that warmer, humid climates will not slow the virus in the initial stages of the pandemic," said study lead author Rachel Baker, post-doctoral researcher at Princeton, in a statement from the university.

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"The virus will spread quickly, whatever the weather"

Climate, especially humidity, plays a role in the spread of other coronaviruses and influenza, but this factor should be limited compared to another much more important factor in the current pandemic, researchers say: the low collective immunity against Sars-Cov-2. That is to say that the reserve of people to be infected remains amply sufficient to ensure rapid progression. "The virus will spread quickly, whatever the weather," added the researcher.

Towards a seasonal virus after the pandemic? 

In the absence of control measures or a vaccine, say the authors of this study, the coronavirus will therefore gradually contaminate a larger part of the population. It was only after that he could become seasonal, like his cousins. "Other human coronaviruses like the common cold are highly dependent on seasonal factors, peaking during the winter outside the tropics," says Professor Bryan Grenfell. "If, as is likely, the new coronavirus is also seasonal, it can be expected to turn into a winter virus as it becomes endemic in the population."

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The team modeled several scenarios for Sars-Cov-2, based on what has been observed with influenza viruses and two known cold-causing coronaviruses, and by simulating what would happen in several regions of the country. globe, under different temperatures and humidity levels. "Our results imply that tropical and temperate regions must prepare for severe epidemics, and that summer temperatures will not contain the spread of infections," conclude the researchers.