The search for the origins of the Covid pandemic has stalled and the window for solving the mystery is “closing fast,” a team of UN scientists has warned.
In a commentary published in the journal Nature, experts recruited by the World Health Organisation said the investigation of the origins is at “a critical juncture” requiring urgent collaboration, but has instead come to a standstill.
They said that Chinese officials are still reluctant to share some raw data, citing concerns over patient confidentiality.
An initial report by the WHO team based on a January mission to Wuhan, China, concluded that the Sars-CoV-2 virus probably jumped from bats to humans via an intermediate animal.
In their analysis, published in March, the WHO team concluded the virus probably jumped to humans from animals and they described the possibility of a laboratory leak as “extremely unlikely.”
But the WHO experts said their report was intended only as a first step, adding: “The window of opportunity for conducting this crucial inquiry is closing fast: any delay will render some of the studies biologically impossible.”
“As SARS-CoV-2 antibodies wane, so collecting further samples and testing people who might have been exposed before December 2019 will yield diminishing returns”, they said.
China said on Wednesday that officials should “concentrate on other possible avenues that may help trace the origin” of Covid-19 and suggested studies should be pursued in other countries.
Tracing the biological trail back to the earliest pockets of the disease becomes more difficult as evidence disappears or becomes corrupted.
The statement comes less than two weeks after the WHO, in a bid to revive the probe, urged China to hand over information on the earliest Covid-19 cases.
This should include Covid data for 174 infections identified in December 2019 that China failed to share during the initial investigation, the WHO experts said.
WHO investigators said “it was agreed” at the time that a second phase of research would fill in this gap.
But China pushed back against the WHO request earlier this month, saying the January investigation should suffice and that calls for further data were motivated by politics, not science.
Beijing has especially bridled at the suggestion that the virus may have escaped from the Wuhan virology lab.
On Tuesday, US intelligence agencies presented President Joe Biden with a report looking at both the animal transmission and “lab-leak” hypotheses. The findings were described as inconclusive.
In its comment, the WHO team said that current data does not support the lab-leak scenario, and none of six priorities for further research alluded to this possibility.
Rather, the scientists emphasised the need to trace the earliest cases of Covid through disease reporting and antibody surveys, inside and outside China.
They also called for further investigation of wildlife farms and wild bats.