First COVID-19 case could have emerged in China in Oct 2019 - study
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[June 25, 2021]
By David Stanway
SHANGHAI (Reuters) -The virus that causes
COVID-19 could have started spreading in China as early as October 2019,
two months before the first case was identified in the central city of
Wuhan, a new study showed on Friday.
Researchers from Britain's University of Kent used methods from
conservation science to estimate that SARS-CoV-2 first appeared from
early October to mid-November 2019, according to a paper published in
the PLOS Pathogens journal.
The most likely date for the virus's emergence was Nov. 17, 2019, and it
had probably already spread globally by January 2020, they estimated.
China's first official COVID-19 case was in December 2019 and was linked
to Wuhan's Huanan seafood market.
However, some early cases had no known connection with Huanan, implying
that SARS-CoV-2 was already circulating before it reached the market.
A joint study published by China and the World Health Organization at
the end of March acknowledged there could have been sporadic human
infections before the Wuhan outbreak.
In a paper released in preprint form this week, Jesse Bloom of the Fred
Hutchinson Cancer Research Center in Seattle recovered deleted
sequencing data from early COVID-19 cases in China.
The data showed that samples taken from the Huanan market were "not
representative" of SARS-CoV-2 as a whole, and were a variant of a
progenitor sequence circulating earlier, which spread to other parts of
China.
The U.S. National Institutes of Health confirmed to Reuters that the
samples used in the study were submitted to the Sequence Read Archive
(SRA) in March 2020 and later deleted at the request of Chinese
investigators, who said they would be updated and submitted to another
archive.
Critics said the deletion was further evidence that China was trying to
cover up the origins of COVID-19.
"Why would scientists ask international databases to delete key data
that informs us about how COVID-19 began in Wuhan?" said Alina Chan, a
researcher with Harvard's Broad Institute, writing on Twitter.
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Workers in PPE spray the ground with diinfectant in Baishazhou
market during a visit of World Health Organization (WHO) team tasked
with investigating the origins of the coronavirus (COVID-19)
pandemic, in Wuhan, Hubei province, China, January 31, 2021.
REUTERS/Thomas Peter
Another study by Australian scientists, published on
Thursday in the Scientific Reports journal, used genomic data to
show SARS-CoV-2 binds to human receptors far more easily than other
species, suggesting it was already adapted to humans when it first
emerged.
It said it was possible there was another unidentified animal with
even stronger affinity that served as an intermediary species, but
the hypothesis that it leaked from the lab could not be ruled out.
"While it is clear early viruses had a high propensity for human
receptors, that doesn't mean they were 'man-made'," said Dominic
Dwyer, infectious disease expert at Australia's Westmead Hospital
who was part of the WHO team investigating COVID-19 in Wuhan this
year.
"Such conclusions remain speculative," he said.
Serum samples still needed to be tested to make a stronger case
about COVID-19's origins, said Stuart Turville, associate professor
at the Kirby Institute, an Australian medical research organisation
who was responding to the University of Kent study.
"Unfortunately with the current pressure of the lab leak hypothesis
and the sensitivities in doing this follow-up research in China, it
may be some time till we see reports like that," he said.
(Reporting by David Stanway; Additional reporting by Kanishka Singh
and Vishal Vivek in Bengaluru;Editing by Raju Gopalakrishnan and Kim
Coghill)
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