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The least likely source: a laboratory leak, concluded the WHO’s joint international team.
The WHO is expected to release the final report of its investigation into the origins of the coronavirus on Tuesday, but a draft version of the report obtained by CNN shows that there is still no smoking gun and no evidence to suggest the virus is spreading before. the very end of 2019.
The report gives four possible sources for the virus and the most likely scenario is via an intermediate animal host, possibly a wild animal captured and then raised on a farm.
But the investigation did not find what other animal was infected with a bat – believed to be the most likely original source of the virus – and may then have passed it on to a human. “The possible intermediate host of SARS-CoV-2 remains elusive,” one reads.
Then there is likely direct transmission from one of the animals known to carry a similar coronavirus, such as a bat or a pangolin. Transmission from frozen or chilled foods is possible but not likely, and the least likely is accidental release in the laboratory, according to the report.
The report says it is “extremely unlikely”. “There are no records of viruses closely related to SARS-CoV-2 in any laboratory before December 2019, nor of genomes that in combination could provide a SARS-CoV-2 genome,” it reads. “In view of the above, a laboratory origin of the pandemic was considered extremely unlikely.”
Frozen foods are also not a likely source, the report says. “There is no conclusive evidence of food transmission of SARS-CoV-2 and the likelihood of cold chain contamination by virus from a reservoir is very low,” he says.
The role of the Huanan seafood market in Wuhan is also unclear. It is possible that the market was not the original source of the outbreak, but the crowds that gathered in the market – which was densely populated, with a roof and open sewers – may have -be amplified the spread of the virus.
Market sampling revealed the virus on surfaces, but not in samples taken from animals or food sold in the market. Additionally, there is evidence that the virus was circulating before the outbreak in Huanan market – including other markets.
“Many of the early cases were associated with the Huanan market, but a similar number of cases were associated with other markets and some were not associated with any market. Transmission within the wider community in December might explain cases not associated with the Huanan market, which, combined with the presence of early cases not associated with this market, could suggest that the Huanan market was not the initial source of the outbreak, ”the report added.
“No definitive conclusion about the role of Huanan’s market in causing the outbreak, or how the infection was introduced to the market, can be drawn at this time,” the report concludes.
The report recommends more testing of blood samples taken and stored before the first outbreak in December, more testing on animals in Southeast Asia, and further study of mass gatherings that may have contributed to the spread. virus.
The report was written by a joint international team of 17 Chinese experts and 17 experts from other countries, WHO, the Global Outbreak Alert and Response Network (GOARN) and the World Organization for Animal Health (OIE). The Food and Agriculture Organization of the United Nations (FAO) participated as an observer.
“Following the first online meetings, a joint study was conducted over a 28-day period from January 14 to February 10, 2021 in Wuhan city, People’s Republic of China,” the report said.
The team looked for evidence that the virus was circulating in China before anyone knew it.
“The Epidemiology Working Group took a close look at the possibilities of identifying previous cases of COVID-19 through morbidity (disease) surveillance studies due to respiratory illnesses in Wuhan and surrounding areas at the end of of 2019 ”, we read.
“It also relied on national sentinel surveillance data; laboratory confirmations of illness; retail drugstore purchase reports for antipyretics (anti-fever), cold and cough medications; a convenient subset of stored samples of more than 4,500 samples from research projects in the second half of 2019 stored at various hospitals in Wuhan, the rest of Hubei Province and other provinces. In none of these studies was there evidence of an impact of the causative agent of COVID-19 on morbidity in the months leading up to the COVID-19 outbreak. “
The report suggests additional checks on farms as a possible source of the virus.
“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 says. .
Animals such as mink and rabbits are susceptible to the virus, the report notes. Mink farms in several countries have been the source of Covid-19 epidemics.
“The growing number of SARS-CoV-2 susceptible animals includes animals reared at sufficient densities to allow potential enzootic circulation.” High density agriculture is common in many places around the world and also includes many species of livestock. as farmed fauna. There was an extensive network of domesticated wild animal farms, supplying farmed wildlife. “
US White House press secretary Jen Psaki said the report was under review by federal government agencies, including the CDC, the Food and Drug Administration, the National Institutes of Health and other. Psaki said these public health experts “will review this report intensively and expeditiously.”
“We will wait until this review is completed. We have made it clear that an independent and technically sound investigation is our goal, and once that is reviewed, we will have an assessment of what to do next,” she said. a briefing.
Psaki said the United States was communicating with its allies “to share our current concerns, which we have expressed in the past, of course, about the process and our scientific analysis of the report itself.”
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