Initial WHO report finds no conclusive evidence of SARS-CoV-2 origin
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A team of investigators who traveled to China did not find conclusive evidence of the origin of SARS-CoV-2, although they said humans were “likely to very likely” exposed through an intermediary animal host.
In a 120-page report released Tuesday by WHO, the investigators also said that a direct zoonotic spillover to humans was “possible to likely,” and that it was also “possible” that humans were exposed through the cold food chain.
They said it was “extremely unlikely” that the coronavirus was introduced to the general public through a laboratory incident — a scenario that received renewed attention recently after former CDC Director Robert R. Redfield, MD, told CNN that he believed the virus originated in a lab.
The findings were based on a trip by an international team of experts to Wuhan earlier this year. Based on phylogenetic analyses, the investigators said bats appear to be the reservoir for SARS-CoV-2, but no intermediate host has been identified.
The investigators confirmed widespread SARS-CoV-2 contamination of surfaces in an animal market in Wuhan that has long been speculated as the origin of the virus’ introduction to humans. The contamination was “compatible with virus shedding from infected people in the market at the end of December 2019,” they said. However, extensive testing of animal products in the market did not turn up evidence of the virus.
“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 markets,” the investigators wrote, noting that they could draw “no firm conclusion” about the Huanan market’s role in the origin of the outbreak.
The investigators said they found “little evidence” of SARS-CoV-2 transmission before December 2019 but could not rule out the possibility that some transmission was occurring at low levels.
“As far as WHO is concerned, all hypotheses remain on the table,” WHO Director General Tedros Adhanom Ghebreyesus, PhD, MSc, said in a statement. “This report is a very important beginning, but it is not the end.”
Tedros recommended that further research include a full analysis of the animal trade in Wuhan, and agreed with investigators that farmers, suppliers and their contacts also be interviewed.
Peter K. Ben Embarek, PhD, who led the WHO team, said identifying an intermediate host has been difficult.
“We're conducting a large number of surveys on animals, different types of animals, wild animals, animals from zoos, animals from farms, domestic animals, etc. Dozens of thousands of animals were tested and all [were] negative,” Ben Embarek said during a press conference.
According to the report, human-to-human transmission of SARS-CoV-2 began before the initiation of any control measures, which subsequently led to a high rate of spread around Wuhan to other parts of Hubei province and China. There was a lot of movement from Wuhan during the 2020 Chinese New Year, leading to spread beyond the city, investigators said.
References:
Former CDC director believes virus came from lab in China. [VIDEO]. CNN. https://www.cnn.com/videos/health/2021/03/26/sanjay-gupta-exclusive-robert-redfield-coronavirus-opinion-origin-sot-intv-newday-vpx.cnn. Published March 26, 2021. Accessed March 30, 2021.
WHO. WHO-convened global study of origins of SARS-CoV-2: China part. https://www.who.int/publications/i/item/who-convened-global-study-of-origins-of-sars-cov-2-china-part. Accessed March 30, 2021.
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I don’t think there was anything terribly novel in the report, which I think was to be expected, given that the Chinese government controls a lot of the news and had to authorize the report. They really controlled a lot of what the investigators had access to, and the research that the investigators saw was presented to them by Chinese scientists. So, I think it feels very controlled.
I think there's still a lot more information that feels like it's missing, and it's unclear if we’ll ever get that information, because we are now over a year from the first cases of the coronavirus in China, and the longer you are from the beginning of an outbreak, the harder it is to understand the origins of the disease
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