China might be cleared as the original source of the coronavirus outbreak, with a World Health Organisation investigation now turning its attention to the rest of the world.
The 12-day investigation in the Chinese city of Wuhan concluded this week COVID-19 “most likely” originated in a bat, and spread to humans through another – as yet unidentified – mammal.
“All the work that has been done on the virus and trying to identify its origin continue to point toward a natural reservoir,” Dr Peter K. Ben Embarek, a WHO food safety scientist and team leader of the investigation.
“The possible path from whatever original animal species all the way through to the Huanan market could have taken a very long and convoluted path involving also movements across borders.”
Leak from lab ruled out, possibly China too
The investigators ruled out the possibility the virus emerged from a laboratory studying bat coronaviruses in Wuhan, saying this avenue will no longer be explored.
However, the WHO team lent support to the idea the virus originated outside of China – and have said this will be part of further investigations.
One theory, pushed by China, is the virus infected imported frozen meats.
In a report from the BBC, the investigators called for further investigation into the possibility of “cold chain” transmission, referring to the transport and trade of frozen food.
Dr Peter Daszak, a member of the WHO team, said “the focus on where the origins that led to COVID-19 might be, could be shifted to South East Asia”.
He said the team had done “a lot of work in China and if you map that back it starts to point towards the border and we know that there is very little surveillance on the other side in the whole region of South East Asia.”
Independent expert reaction
The overall opinion voiced by Australian researchers not involved with the investigation can be summed up by that of Dr Hassan Vally, Associate Professor in Epidemiology at La Trobe University.
“There are no surprises here in the report …There really wasn’t any plausible reason for us to think anything else had occurred given what we know about new pathogens and their origins,” Dr Vally said.
There was, however, a sting in many responses – Dr Vally questioned the value of the investigation because of its year-long delay:
“Having said this … as a scientist and epidemiologist I do remain sceptical as to the value of visiting Wuhan a year after the start of the pandemic,” he said.
“This international investigation should have been able to occur at the beginning of the pandemic, and it is a missed opportunity that this was not able to be organised earlier.”
Professor Nikolai Petrovsky, from the College of Medicine and Public Health at Flinders University, and Research Director of Vaxine Pty Ltd questioned the evidence for the virus originating outside of China. In a prepared statement, he wrote:
“As expected, no conclusive or novel findings have been made by the panel after their two-week visit to China.
“It does however go further than many might have expected in emphasising two key assertions previously made by the Chinese government that the virus source of the pandemic may lie outside of China, and the possibility the transmission into China occurred via frozen food.”
He said that the scientific evidence behind both these assertions by the WHO panel “remains unclear, beyond relatively weak data already in the public domain”.
Lab accident ruled out too quickly
Professor Raina MacIntyre is head of the Biosecurity Program at the Kirby Institute at the University of NSW, and was surprised the investigators concluded the outbreak started in December and not earlier.
She cited data from the US and Europe that showed the virus was in circulation there by December 2019, which sits counter to the WHO’s finding.
She pointed to reports of a flu-like illness at the World Military Games in October in Wuhan, and also of possible ‘patient zeroes’ identified in mid November 2019.
Professor MacIntyre further brought into question Spanish wastewater samples, taken in March 2019, that returned positive results for COVID-19.