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Science News

Factbox: WHO-China report on virus origins says lab leak extremely unlikely

GENEVA (Reuters) - Here is a summary of the main findings of an international team of experts, led by the World Health Organization (WHO), which investigated the origins of the new coronvirus first identified in Wuhan, China, in late 2019.

FILE PHOTO: The ultrastructural morphology exhibited by the 2019 Novel Coronavirus (2019-nCoV), which was identified as the cause of an outbreak of respiratory illness first detected in Wuhan, China, is seen in an illustration released by the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, U.S. January 29, 2020. Alissa Eckert, MS; Dan Higgins, MAM/CDC/Handout via REUTERS/File Photo

Reuters has seen the joint WHO-China report, which is due to be published on Tuesday at 1400 GMT.

ON LIKELY SOURCES

• direct zoonotic (animal-to-human) spillover is considered to be a possible-to-likely pathway;

• introduction through an intermediate animal host is considered to be a likely to very likely pathway

• introduction through cold/food chain products is considered a possible pathway

• introduction through a laboratory incident was considered to be an extremely unlikely pathway

ON THE ROLE OF THE HUANAN FARM MARKET IN WUHAN, CHINA

Many early human cases were associated with the Huanan seafood market in Wuhan, which also sold wildlife, “but a similar number of cases were associated with other markets and some were not associated with any market”, the report said.

“No firm conclusion therefore about the role of the Huanan market in the origin of the outbreak, or how the infection was introduced into the market, can currently be drawn.”

ON WHETHER THE VIRUS WAS CIRCULATING OUTSIDE CHINA FIRST

“The findings suggest that circulation of SARS-CoV-2 preceded the initial detection of cases by several weeks. Some of the suspected positive samples were detected even earlier than the first case in Wuhan, suggesting the possibility of missed circulation in other countries.

So far, however, the quality of the studies is limited. Nonetheless, it is important to investigate these potential early events.”

Reporting by Michael Shields in Zurich and Stephanie Nebehay in Geneva; editing by Gareth Jones

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