A leading public health expert has made a disturbing prediction about how many people could be infected with the potentially deadly coronavirus if it can’t be controlled or contained.

Professor Gabriel Leung, an epidemiologist and chair of public health medicine at Hong Kong University, believes coronavirus could infect 60 per cent of the world’s population if strict measures like the ones being implemented in China are not taken.

In the video above: Coronavirus toll climbs past 1000

The death toll from coronavirus has now overtaken that of the SARS epidemic of 2002-3, passing 1000 dead by Tuesday.

But the World Health Organisation (WHO) has issued a stark warning that such numbers could be just “the tip of the iceberg.”

Speaking to The Guardian UK, Prof Leung said each infected person could go on to transmit the virus to another 2.5 people, meaning an “attack rate” of 60 to 80 per cent.

Even if the fatality rate was one per cent, that would still be a huge global death toll, he said.

Patients in a makeshift hospital in Wuhan, China. Credit: Barcroft Media / Barcroft Media via Getty Images

In January, Prof Leung wrote an article in the medical journal The Lancet, warning that viral outbreaks were likely to grow exponentially in Chinese cities, as the infection spread beyond the “ground zero” of Wuhan.

People in other cities could be infected within as little as two weeks if there continued to be unrestricted movement between residents in different cities, he said.

Prof Leung said there may not be a mass infection of two-thirds of the world’s population in one hit; rather, the epidemic might come in “waves.”

“Maybe the virus is going to attenuate its lethality because it certainly doesn’t help if it kills everybody in its path, because it will get killed as well,” he said.

People wearing face masks at the checkout counter with their grocery at a supermarket on February 9, 2020 in Singapore. Credit: Ore Huiying / Getty Images

Health authorities are now looking into whether the strict containment measures enforced in Wuhan - a city that is essentially in lockdown - are working.

“Have these massive public health interventions, social distancing, and mobility restrictions worked in China?” he said.

“If so, how can we roll them out (in other places), or is it not possible?”

Plan B

If the virus cannot be contained, public health authorities will have to move on to Plan B - working out how to reduce its effects and fatality rate.

Quarantines, regular testing, restriction of movement amongst people, and attempts to develop a vaccine are crucial.

Chinese President Xi Jinping, left, wears a protective face mask and receives a temperature check in Beijing on Monday. Credit: Pang Xinglei / AP

At this stage, Prof Leung said, researchers still do not know whether the virus is transmitted via droplets from coughs or via airborne particles.

“It’s very difficult told do that kind of careful detailed (research) work when everything is raging,” he said.

“And unless it’s raging, you are unlikely to get enough confirmed cases. With SARS, we never got a chance to do these kinds of studies.”

‘Grave threat’

On Tuesday, WHO director-general Tedros Adhanom Ghebreyesus described the coronavirus as a “very grave threat,” launching an appeal for sharing virus samples and speeding up research into drugs and vaccines to combat the epidemic.

Nearly 170 laboratories globally have the right technology to diagnose the coronavirus, WHO says. Credit: EPA

He was addressing the start of a two-day meeting aimed at accelerating development of drugs, diagnostics and vaccines against the flu-like virus amid growing concerns about its ability to spread.

“With 99 per cent of cases in China, this remains very much an emergency for that country but one that holds a very grave threat for the rest of the world,” he told more than 400 researchers and national authorities.

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Tedros, speaking to reporters, referred to “some concerning instances of onward transmission from people with no travel history to China”, citing cases this week in France and Britain.

Five British nationals were diagnosed with the coronavirus in France after staying in the same ski chalet with a person who had been in Singapore.

“The detection of this small number of cases could be the spark that becomes a bigger fire. But for now it’s only a spark. Our objective remains containment,” he said.

- with AAP