WHO report: Multiple hypotheses into Covid origins, yet no clear answers

Tedros Adhanom Ghebreyesus, Director General of World Health Organization. (Credit: Keystone / Martial Trezzini

Coronavirus most likely spread from bats to humans through another animal, according to a long-awaited report by the World Health Organization (WHO) into the origins of Covid-19.

The findings, based on a visit by a WHO team of experts to Wuhan earlier this year, offer little fresh insight into how the virus first emerged, leaving many questions still unanswered.

Looking at the chances that it spread through a lab leak is “extremely unlikely”, according to a draft copy obtained by The Associated Press, who first reported the story.

It also casts doubt on another theory that the virus may have emerged in China because of imported frozen food, saying that the “probability of a cold-chain contamination with the virus from a reservoir is very low”.

The WHO’s team of experts already briefed on their initial findings following their return from China last month.  However the report will provide more detail on the reasoning behind the conclusions of the health experts who undertook the initial investigation.

In a briefing on Monday, the head of the WHO said the long-awaited report will be released publicly on Tuesday but that further study is required.

“As I have said all hypotheses are on the table and warrant complete and further studies,” said Tedros Adhanom Ghebreyesus.

Read also: Answers still missing after WHO China probe into Covid origins.

AP received what it said appeared to be a near-final version of the 123 page report in which scientists outlined several theories that might explain how the virus first spread to humans.

During a lengthy press conference in Wuhan on 9 February at the end of the mission, the experts made clear that they could not yet draw any firm conclusions. But they said they had worked to rank a number of hypotheses according to how likely they were. A spillover from bats via another animal is seen as the most likely scenario.

“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.

Having a  “missing link”, leaves room for a more likely scenario, that the virus first jumped from bats to another animal which then infected humans.

“The scenario including introduction through an intermediary host was considered to be likely to very likely.”

Searching for the answers where the virus was first believed to have begun has been shrouded in controversy since the start of the pandemic, with China criticised for delaying access to WHO scientists. The report’s release has been repeatedly delayed, raising questions about whether China was trying to skew the conclusions to divert blame for the pandemic, according to the AP.

Although the probe has been highly politicised, all stakeholders including governments and scientists believe deciphering how and where the virus started is an important clue in reducing the risk of future pandemics.

At the same briefing on Monday German international development minister Gerd Mueller said he welcomed China's cooperation with the probe.