The coronavirus epidemic could grip about two-thirds of the world’s population if the deadly bug is not controlled, a top public health official said — as another expert predicted that cases in China could peak this month and fade away by April.

Professor Gabriel Leung, chair of public health medicine at Hong Kong University, told the Guardian he was examining the implications of the World Health Organization’s Monday warning that cases of coronavirus spreading outside China are the “tip of the iceberg.”

Most experts believe that each person infected can go on to transmit coronavirus to about 2.5 other people — creating an “attack rate” of 60 to 80 per cent, Leung told the paper.

“Sixty per cent of the world’s population is an awfully big number,” he said.

Even with a general fatality rate as low as 1 per cent — a possibility once milder cases are taken into account — there could still be a massive global death toll, he added.

Meanwhile, experts are attempting to map out the likely course of the illness, Leung told the Guardian.

“Is 60 to 80 per cent of the world’s population going to get infected?” he said. “Maybe not. Maybe this will come in waves. Maybe the virus is going to attenuate its lethality because it certainly doesn’t help it if it kills everybody in its path because it will get killed as well.”

Health officials are also attempting to determine whether restrictions put in place in Wuhan — the epicentre of the outbreak — as well as other cities, have made a positive impact.

“Have these massive public health interventions, social distancing, and mobility restrictions worked in China?” Leung asked. “If so, how can we roll them out, or is it not possible?”

Meanwhile, Zhong Nashan, 83, China’s foremost medical adviser on the outbreak, told Reuters that the numbers of new cases are dipping in some parts of the country. The epidemic may peak this month and then plateau, he said.

“I hope this outbreak or this event may be over in something like April,” said Zhong, an epidemiologist best known for his role in combating a surge of severe acute respiratory syndrome cases in 2003.

But World Health Organization chief Tedros Adhanom Ghebreyesus warned that the epidemic is far from over.

“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,” Tedros told researchers gathered in Geneva on Tuesday.

A total of 1,017 people have died of coronavirus in China, where a total of 42,708 cases have been reported, the World Health Organization said Tuesday.

Only 319 cases have been confirmed in 24 other countries and territories outside mainland China, the WHO and Chinese health officials said. One person has died in Hong Kong and another in the Philippines.