By Maggie Fox and Sandi Sidhu, CNN
(CNN) – Covid-19 probably came to humans via animals, and likely began spreading no more than a month or two before it became known in December 2019, according to a draft World Health Organization report.
The most unlikely source: a laboratory leak, the WHO’s joint international team concluded.
The WHO is scheduled to release a final report on its investigation into the origins of the coronavirus on Tuesday, but a draft version of the report obtained by CNN suggests there is still no smoking gun and no evidence to suggest the virus spread earlier than late 2019.
The report provides four possible sources of the virus and the most likely scenario is through an intermediate animal host, possibly a wild animal captured and then raised on a farm.
But investigations have yet to find out what other animals were infected by the bats – which are thought to be the most likely original source of the virus – and then may have passed it on to humans. “The possibility of an intermediate host for SARS-CoV-2 remains elusive,” the statement read.
The next possibility is direct transmission from one of the animals known to carry a similar coronavirus, such as bats or pangolins. Likely but unlikely was transmission from frozen or chilled food, and less likely to be accidental laboratory release, the report found.
Former Director of the US Centers for Disease Control and Prevention Dr. Robert Redfield said Dr. CNN’s Sanjay Gupta that his personal opinion was that the virus was released from the laboratory.
The report said this was “very unlikely”. “There is no record of the virus being closely related to SARS-CoV-2 in any laboratory prior to December 2019, or that the combined genome could produce the SARS-CoV-2 genome,” he wrote. “Given the above, the laboratory origin of a pandemic is considered very unlikely.”
Independent researchers have been saying this for months. Viral genome testing shows it was not engineered in the laboratory but transmitted naturally from animals – as did the SARS virus which infected 8,000 people worldwide in 2002-2004 before being discontinued.
Frozen food is also unlikely to be the source, the report said. “There is no conclusive evidence for foodborne transmission of SARS-CoV-2 and the likelihood of cold chain contamination with the virus from a reservoir is very low,” he said.
The role of the Huanan seafood market in Wuhan is also unclear. It is possible that the market is not the original source of the outbreak, but the crowds gathered in the market – which is crowded, with open roofs and gutters – may have amplified the spread of the virus.
Market sampling raises the virus on the surface but not samples taken from animals or food sold in the market. Plus, there is evidence the virus was circulating before the Huanan market outbreak – including in other markets.
“Many of the early cases were linked to the Huanan market, but a number of similar cases were linked to other markets and some not to any market. Transmission in the wider community in December could explain cases not related to the Huanan market which, together with the initial cases unrelated to the market, could indicate that the Huanan market was not the original source of the outbreak, ”the report is added.
“Therefore, no definite conclusions about the role of the Huanan market in the origin of the outbreak, or how the infection entered the market, can at this time be drawn,” the report concluded.
The report recommends more testing of blood samples taken and stored before the first outbreak in December, more animal testing from Southeast Asia, and more in-depth studies of mass encounters that could help spread the virus.
The report was written by a joint international team of 17 Chinese experts plus 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) participates as an observer.
“After the initial online meeting, the joint study was carried out over a 28-day period from January 14 to February 10, 2021 in the city of Wuhan, People’s Republic of China,” reads the report.
The team looked for evidence the virus was circulating in China before anyone knew it.
“The epidemiology working group is closely examining the possibility of identifying early cases of COVID-19 through studies of surveillance of respiratory disease morbidity (disease) in and around Wuhan by the end of 2019,” he wrote.
“It also uses national sentinel surveillance data; laboratory confirmation of disease; reports on purchases of retail pharmacies for antipyretics (fever relievers), colds and cough medicines; the convenience part of the sample housed more than 4,500 research project samples from the second half of 2019 that were housed in various hospitals in Wuhan, throughout Hubei Province, and other provinces. Neither of these studies has demonstrated the impact of the causative agent of COVID-19 on morbidity in the months preceding the COVID-19 outbreak. “
The report suggests further inspection of farms as a possible source of the virus.
“Although the closest related virus has been found in bats, the evolutionary distance between this bat virus and SARS-CoV-2 is estimated to be several decades, indicating a missing link,” the report wrote.
Animals such as mink and rabbits are susceptible to the virus, the report said. Mink farming in several countries is the cause of the outbreak of Covid-19.
“Increasing numbers of animals that are shown to be susceptible to SARS-CoV-2 include farmed animals with sufficient densities to allow enzootic circulation. High density livestock farming is common in many parts of the world and includes many species of farmed livestock and wildlife. There is a large network of domesticated wild animal farms, supplying cultivated wildlife. “
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