Coronavirus: "The epidemic could affect 60% of the world population", really?

Will two thirds of the planet's inhabitants start coughing, become feverish and, for some, die from Covid-19? "The coronavirus could infect 60% of the world's population if not controlled, " the Guardian headlined in a February 11 article, citing renowned Hong Kong epidemiologist Gabriel Leung.

Although conditional, this sentence, repeated since in many media, is enough to worry almost everyone about the evolution of this epidemic which appeared in China in December 2019 and which has already infected more than 60,000 people.

"Most experts claim that infected individuals spread the virus to an average of 2.5 people," the British newspaper wrote. Which gives an attack rate of 60-80%. "It's a terribly large figure," then acknowledges the Hong Kong researcher. And to add, further on in the article: "Will 60 to 80% of the world population be infected?" Maybe not. Maybe it will come in waves. Maybe the virus will reduce its lethality. "

Gabriel Leung clarified his comments in tweets on Thursday, stating that the Guardian quote refers to his response when asked about the results of modeling generated by "a Japanese colleague." "In addition, I also said that the attack rate of 70-80% does not make sense in itself because it is necessary to know 1- over what period this could (and not should) occur, 2- the severity of the infection. "

The worst-case scenario

Predicting that 60% of the planet can be infected, "it is going a bit quickly in speculation", also believes Marie-Paule Kieny, specialist in viral diseases at Inserm and former deputy director of the World Organization for health. Should this worst-case scenario be excluded? " No. »Is it likely? "Probably not. There is still a window of opportunity to close the door to this kind of forecast, ”continues the researcher.

“Such modeling is useful because it is a way of saying to countries: if you do nothing, watch what can happen . It awakens and raises awareness among states , adds Arnaud Fontanet, head of the epidemiology unit for emerging diseases at the Institut Pasteur. But it doesn't make much sense right now, because action is being taken. "

Many airlines have announced that they are extending the suspension of their routes to China. In the big cities of this country, where the epidemic started, the streets are still deserted despite the timid resumption of work, after the prolonged holidays of the New Year. Telework is favored, the taking of temperatures are compulsory before entering most buildings and offices are disinfected. In Vietnam, the commune of 10,000 inhabitants, Son Loi, near Hanoi, has been in quarantine since the discovery of five Covid-19 positive cases. International gatherings, such as the World Mobile Show in Barcelona or the Chinese Formula 1 Grand Prix, are canceled.

"People want certainty"

The main fear is to see the epidemic spread to countries with fragile health systems. This could cause “chaos,” in the words of the Director-General of WHO, Tedros Adhanom Ghebreyesus. "To avoid this, we will have to determine which measures are really effective in the fight against the epidemic and apply them where necessary", details Marie-Paule Kieny.

Newsletter - The essentials of the news

I'm registering

Your email address is collected by Le Parisien to allow you to receive our news and commercial offers. Find out more

VIDEO. In Asia, images of massive disinfection of streets, stations, hospitals, etc.

"But how long can you close an entire city?" wonders Gabriel Leung, in the Guardian article. How long can you keep people from shopping in malls? And if you remove (these restrictions), will the virus come back? So these are real questions. "

"There are still so many unknowns around the new coronavirus," recalls Marie-Paule Kieny. But people don't like strangers. They want certainties. We must communicate balanced information: do not minimize the risk, do not inflate it either, as this can lead to panic scenes, rushes in stores, create shortages ... We must be able to say: we don't know . "