Chinese scientists offer new study to shift back date of Covid-19 spread in US

Researchers use US public data to draw the conclusion but did not calculate how many cases were imported
China has become more overt in pointing finger at the US, particularly after Biden tasked US intelligence with investigating the lab-leak theory

Coronavirus pandemic

Josephine Ma

Published: 9:00pm, 23 Sep 2021

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It was “highly probable” Covid-19 started to spread in the United States in September 2019, a group of Chinese scientists said in a new paper published on the preprint platform of the Chinese Academy of Sciences.

In the paper, which has not been peer reviewed, the authors said they used US government public data about the numbers of diagnoses and tests as well as mortality figures from March 2020, and they developed formulas to infer the probability of Covid-19 cases in the US in 2019.

They concluded there was a 50 per cent chance the first case of Covid-19 occurred in the US between August and October 2019, earlier than the official date.

“The calculation results show that the Covid-19 epidemic has a high probability of beginning to spread in the US in September 2019,” they said in the paper published on ChinaXiv.org.

It also said that based on the data from 12 representative regions in the US, a range of probable early cases could be inferred, with Rhode Island the possible site of the earliest case on April 26, 2019, and the latest in November 2019 in Delaware.

However, the authors did not take into account that many early cases in the US government public records were imported cases from multiple sources in Europe or Asia, but projected backwards to infer the date of a possible first case in the 12 regions they looked at while applying their formulas.

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“It’s a poor quality analysis, I doubt it can be published in an international journal,” said a public health expert who declined to be named.

“Any analysis of test-positive rates should account for how testing is being done, and interpolation beyond the range of the observed data is always difficult,” the expert added.

“Early in the pandemic most countries focused on testing tourists from China rather than locals, so the early data is not really indicative of local transmission.”

China has said its first Covid-19 case was recorded in December 2019. The US said its first case was identified on January 20 and the patient had a travel history to Wuhan in central China where the transmission of the virus was first reported.

The paper was written by Zhouwang Yang, a professor of the school of mathematical sciences at University of Science and Technology (UST) of China, Guo Tiande from the CAS and two other scholars from UST.

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It was published as China tries to counter US criticism that it is withholding information about early Covid-19 cases, and amid calls from Western countries and the World Health Organization that more investigation should be done in China on the origin of Covid-19.

Beijing has refused to have further studies conducted in China after the second WHO mission visited the central Chinese city of Wuhan in February this year to investigate the origin of the coronavirus that caused the pandemic. Instead, it said investigations should be carried out in other countries.

In recent months, China has become more explicit in pointing the finger at the US, particularly after US President Joe Biden asked US intelligence to investigate whether the coronavirus was leaked from a Wuhan laboratory, a theory that was first dismissed by prominent scientists during the early days of the pandemic but has regained attention in recent months.

Beijing responded by drawing attention to a germ laboratory at the Fort Detrick military base in Maryland, which it said was another potential source of the virus, citing a 2019 shutdown over safety violations related to the disposal of dangerous materials.

Separately, the CAS paper used data from the eastern province of Zhejiang and Wuhan to infer the date of the earliest cases in the two places. It said there was a high probability that Covid-19 began to spread in China in late December.

It did not mention Fort Detrick but explained at length its calculation, using data from Maryland.

This article appeared in the South China Morning Post print edition as: covid-19 ‘may have started to spread earlier in u.s.’