WHO report says animals likeliest origin of Covid-19, minimises lab hypothesis
A long-awaited World Health Organization (WHO) report on how the coronavirus causing Covid-19 began to infect humans privileges an animal origin and minimises the possibility of a laboratory leak.
The final report of an international expert mission to the Chinese city where the first Covid-19 outbreak happened in late 2019 says the coronavirus causing the disease most likely had a zoonotic origin, according to news agencies citing leaked copies of the report.
The head of the United Nations health agency said the report would be published on Tuesday and that it was ultimately inconclusive about the origin of the new coronavirus.
“All hypotheses are on the table and warrant complete and further studies,” WHO director-general Tedros Adhanom Ghebreyesus told reporters at a news conference on a separate topic.
The report is the result of a four-week mission to the Chinese city of Wuhan that happened in January and February.
Bats likeliest origin
According to AFP agency, the report explored different hypotheses of the origin of the coronavirus pandemic and ranked them by probability.
The two likeliest supported the consensus around the theory that the SARS-CoV-2 virus evolved in bats and began infecting humans either directly or through an intermediary species.
The agency said the report deemed it was “likely to very likely” the virus began infecting humans through an intermediary species and “possible to likely” the virus jumped directly from bats to humans.
“Although the closest related viruses have been found in bats, the evolutionary distance between these bat viruses and SARS-CoV-2 is estimated to be several decades, suggesting a missing link,” the report said.
“The scenario including introduction through an intermediary host was considered to be likely to very likely,” though it was not clear which animal may have allowed the jump.
The report did not rule out the hypothesis, privileged by Beijing, of transmission through frozen food, since the virus appears capable of surviving at freezing temperatures and “introduction via cold/food chain products is considered possible”.
Lab theory downplayed
The least probability was granted to the hypothesis of a leak from a laboratory, a thesis that gained considerable traction via former United States President Donald Trump.
A handful of academic papers have been published, and several withdrawn, arguing SARS-CoV-2 appeared instantly adapted to infecting humans and suggested it may have been engineered in a laboratory studying SARS-CoV-1, responsible for the 2002–2003 SARS epidemic, or the HIV virus.
The report argued there was no record of a virus resembling SARS-CoV-2 in any laboratory before December 2019 and stressed high safety levels at the Wuhan labs.
“A laboratory origin of the pandemic was considered to be extremely unlikely,” it said.
Criticism over delays
The rankings did not differ substantially from what experts said in Wuhan in February, at which time they had already announced they believed the lab-leak theory was considered the least likely.
The expert team of 10 international investigators, 17 Chinese counterparts and 10 members of other agencies spent four weeks in China in January and February.
Delays in the publication of the final report, drafted in collaboration with the team’s Chinese counterparts, has been blamed on coordination and translation issues.
Criticism was renewed over the United Nations agency’s slow actions getting the team to Wuhan in the first place, more than a year after the first major outbreak of Covid-19 in December 2019.
Determining the source of the pandemic is considered vital for better protecting against future outbreaks.
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