Paris (AFP)

Although certain respiratory viruses are more easily spread during the winter months and become more rare in fine weather, it cannot however be said today that the epidemic of the new coronavirus will end with the arrival of spring.

US President Donald Trump said Monday that "by April, or sometime in April, heat will usually kill this kind of virus," suggesting that it could mean the end of the new coronavirus epidemic. , which is a variety of viruses.

The new coronavirus, which has already killed at least 1,100 people, still contains many unknowns and no treatment is currently available. It is therefore impossible to know how this new pathogen will behave in the coming weeks and months.

While it is tempting to compare the current coronavirus to the seasonal flu virus because of the similarity of certain symptoms and modes of transmission, the flu actually belongs to another family of viruses, the genetically different myxoviruses, making comparisons partly hazardous.

On the other hand, there have already been two deadly epidemics caused by a coronavirus, and therefore genetically closer to the current coronavirus: the SARS (severe acute respiratory syndrome) of 2002-2003 in Asia and the Seas (respiratory syndrome of the Middle East) , detected for the first time in 2012 and still in progress.

At first glance, the SARS epidemic more or less corresponded to the coldest months in the northern hemisphere.

"The first cases occurred around mid-November in Guangdong province (China). SARS did not start spreading around the world until February 21 (2003), when a doctor infected with Guangdong stayed (in) Hong Kong, "said the World Health Organization.

"It is true that the epidemic ended in June in China and that the last case was in July in Taiwan. Some people had speculated: + the virus appeared in winter and disappeared in fine weather, so maybe there is a seasonal character + ", underlines to AFP Professor Arnaud Fontanet specialist in emerging diseases at the Institut Pasteur.

"Perhaps the warming of summer had contributed to the control of the epidemic, but - and this had been discussed in the scientific press -: did the temperature have to do with the end of the epidemic of No one can answer that, "says Arnaud Fontanet.

In addition, the seasonality of a virus does not mean that it disappears the rest of the year: "We know we still find them all year round," notes Professor Fontanet.

- Counter-example of the Sea -

Moreover, Singapore - which has a tropical climate, hot all year round - experienced a case of SARS, at least, in September 2003.

As for the Coronavirus of the Seas, which has circulated in hot regions, mainly in Saudi Arabia, it is "a counter-example" of the idea according to which "heat" would literally kill "this kind of virus", adds Professor Fontanet .

Especially since the stronger spread in winter of certain respiratory viruses can be due to several factors: for example, it is "also because people live more confined when it is cold", notes Arnaud Fontanet. It is "certainly an important factor of transmission and recognized by all", according to him.

The same questions exist for seasonal flu, for which we observe empirically a seasonality but which we cannot explain with certainty.

Whatever the comparisons made with other more or less similar pathogens, we cannot predict how the new coronavirus will behave, warns Isabelle Imbert, coronavirus specialist at the University of Aix-Marseille: "for now the stagnation of new cases of new coronavirus goes in the direction of the SARS scenario but, unfortunately, we have few means at the present time to predict the viral dynamics, "she said.

In any event, even if, in fact, the arrival of warmer temperatures was possibly likely to help contain or even stem the epidemic of the new coronavirus, the health authorities insist on the imperative nature of active measures (screening rapid, quarantine, etc.) to stop its spread.

Measures which according to the WHO made it possible to stem SARS.

© 2020 AFP