COVID-19 origins: What has China done for origins tracing?

A staff member performs random sample check on inactivated COVID-19 vaccines at a packing line of the Sinovac Research & Development Co., Ltd. in Beijing, capital of China, on Dec. 23, 2020. (Xinhua/Zhang Yuwei)

Origins tracing has been one of the priorities of China's scientific research since the COVID-19 outbreak, and Chinese scientists have done a lot of work on this issue, Xu Nanping, vice minister of Science and Technology, said at a recent press conference on COVID-19 origins tracing.

Origins tracing is substantially a scientific matter, so scientific research has played a crucial role in searching for origins of the virus, said Xu.

Responding to the call by the Chinese government to make the utmost effort to find out where the virus came from, Chinese research groups from academic institutes and universities carried out scientific research on a number of priority areas including animals, humans, molecules and the environment.

In terms of tracing animal origins, Xu said researchers conducted nationwide viral tests over wild animals, poultry and livestock in 31 provinces, municipalities and autonomous regions soon after the outbreak, covering dozens of species, such as pigs, cattle, sheep, chickens, ducks, geese, pigeons, turkeys, wild rabbits and wild boars.

"We tested more than 80,000 samples over a short period of time, and no COVID-19 antibodies or positive nucleic acid test results were detected."

The researchers further conducted COVID-19 challenge trials on animals in the lab, and classified them into such groups as "highly susceptible", "not susceptible" or "resistant to COVD-19", which Xu said helped them "further understand the situation and determine the priorities in tracing animal origins."

Through studies on coronaviruses carried by bats and other animals, the researchers found that the suspicious RaTG13bat coronavirus has a remote evolutionary relationship with SARS-CoV-2.

They also detected multiple strains of coronavirus in smuggled pangolins seized by customs, among which the highest genome homology with SARS-CoV-2 is 92.4 percent, lower than RaTG13, but one strain shows 96.9-percent amino acid homology with SARS-CoV-2, higher than that of RaTG13, indicating that pangolin coronavirus may have played a role in the evolution of SARS-CoV-2, Xu explained.

He added that joint efforts with international scientists facilitated the origins tracing work.

By July 19, Chinese researchers and their counterparts from the U.S., the UK and other countries had jointly published 225 articles related to tracing origins of the virus. Chinese and U.S. medical scientists held six dialogues via video link on containment of COVID-19, said Xu.

Efforts on data and information sharing were also beefed up with a database for global sharing established, he added. "By July 19, the 2019 Novel Coronavirus Resource database had garnered and shared more than 2.53 million collections of worldwide SARS-CoV-2 genome sequences, and offered access to almost 300,000 users from 177 countries and regions."

Chinese scientists' work was recognized by experts from the World Health Organization (WHO).

Peter Daszak, a British zoologist and member of the WHO team to Wuhan, told the New York Times about the cooperative and extensive work that Chinese scientists had done.

Daszak said they were provided with new data on their first day, and when asked for more data, "the Chinese scientists would go off, and a couple of days later, they've done the analysis, and we've got new information. It was extremely useful."

He added that what the Chinese scientists did in the Wuhan Huanan seafood wholesale market, where the first cases were linked to in China, was "a very extensive study, swabbing every surface of this place."

"They'd actually done over 900 swabs in the end, a huge amount of work. They had been through the sewage system. They'd been into the air ventilation shaft to look for bats. They'd caught animals around the market," he added.