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Coronavirus: global infections could increase tenfold every 19 days, Chinese study says

South China Morning Post logo South China Morning Post 7/3/2020 Stephen Chen
a group of people standing in front of a building: The coronavirus epidemic is spreading rapidly around the world but Chinese scientists say the situation could get much worse. Photo: AFP © AFP The coronavirus epidemic is spreading rapidly around the world but Chinese scientists say the situation could get much worse. Photo: AFP
  • Nation’s leading geneticist Jin Li calls on the world to ‘take strong actions on public health, using experiences learned from China and Singapore’
  • Chilling forecast based on simple linear model, though research has yet to be peer-reviewed

The number of coronavirus cases outside China will increase tenfold every 19 days if no drastic measures are taken to contain its spread, according to a study by a team of Chinese scientists.

The research, headed by leading geneticist Jin Li at Fudan University in Shanghai, also traced the spread of the virus outside China back to just 34 “unobserved carriers”.

Jin, who is known as China’s “DNA hunter”, said some of those carriers might be asymptomatic and have been present before or about the same time as the coronavirus was first detected in the central Chinese city of Wuhan.

The research paper, which has yet to be peer-reviewed, was published on Monday on Medrxiv.org – a preprint server for health sciences – and was based on data collected until the end of February.

While Jin’s forecast might seem gloomy, the World Health Organisation on Thursday reported 14,768 confirmed cases outside China, or more than 21 times the 683 it reported on February 16.

In Germany alone, the number of new cases tripled to 545 between Tuesday and Thursday, and a similar pattern was observed in France.

Without strong intervention measures, “the number of confirmed patients outside China will increase tenfold in every 19 days”, the researchers said.

If that were to happen, the number of cases around the world would surpass the figure reported in mainland China within a matter of months.

“The situation is dangerous … we call on the world to take strong actions on public health, using experiences learned from China and Singapore,” the researchers said.

Jin is the vice-president of Fudan University, one of China’s most prestigious academic institutions. His earlier research helped to trace the common ancestor of modern-day Chinese to a small group of African people who arrived in Asia about 60,000 years ago, and in 2016, he and his team used cutting-edge genetic analysis to help police catch one of the nation’s most notorious serial killers.

To map the potential spread of the new coronavirus, the researchers used a simple linear model. Given that the publicly available sample size is small, he said other complicated models could lead to confusing or conflicting results.

“The virus-spreading pattern is complex, yet varies across the world,” the researchers said in their paper. “A simple model simplifies the situation and provides a coarse-grained trend estimation.”

After running the model at Fudan University’s computing centre, the team found that the outbreak could be traced back to 34 initial carriers.

“They may have had only mild symptoms and not gone to hospital,” the paper said.

The first known coronavirus carrier outside China was a woman who travelled from Wuhan to Thailand. She tested positive on January 13.

As of Saturday morning, the virus had spread to more than 90 countries on every continent except Antarctica and infected more than 101,000 people.

Other scientists have also warned that the outbreak – which the WHO has yet to call a pandemic – may still be in its initial stages.

In a paper published in January, Dr Ira Longini, a biostatistician and adviser to the WHO, predicted that two-thirds of the global population would become infected.

Harvard University epidemiologist Marc Lipsitch, who visited China after the outbreak, said in an interview with CBS News on Monday that between 40 and 70 per cent of the world’s population might become infected.

“I think there is real reason for people to be concerned,” he said. “I also think that we can turn that concern into actions that will make the situation better.”

Despite the gloomy forecasts, a study published in medical journal The Lancet in January predicted that the number of confirmed cases in China would surpass 160,000 by early February. As of Saturday morning, the total was less than 81,000.

Beijing has been praised for its efforts to contain the spread of the virus in China, which included locking down the whole of Hubei province, of which Wuhan is the capital and which has a population similar to that of France.

A Chinese government scientist working for a United Nations development programme in Beijing said the global number of infections was subject to many factors including the changing of the season and the development of new drugs or vaccines.

If the number of foreign cases continued to rise rapidly, and if other countries “give up”, China’s strict containment measures at home might have been in vain, he said, adding that there could be “unbearable” consequences for the global economy and its people.

China has been shifting its focus away from containment to preventing foreign cases entering the country. It recently introduced a number of travel restrictions for visitors from high-risk countries, including South Korea and Italy.

“These measures can’t last. We cannot shut the world out. Stopping international exchange will be a disaster, especially to China,” said a researcher who asked not to be named due to the sensitivity of the issue.

“In today’s world, nobody can live happily ever after by solving only his own problems.”

This article originally appeared on the South China Morning Post (SCMP), the leading news media reporting on China and Asia. 

Copyright (c) 2020. South China Morning Post Publishers Ltd. All rights reserved.

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