ll hypotheses into the origins of the virus that causes Covid-19 “remain on the table”, global health leaders have said as they called for more research into whether or not the virus could have entered the human population as a result of a laboratory leak.
Th World Health Organisation (WHO) said that “no stone will be left unturned” as it continues its probe into where the virus came from.
The comments come as the team investigating the origins of the virus published its initial report.
Researchers previously outlined initial findings after a visit to Wuhan in China
China has faced claims that the Wuhan Institute of Virology could be the suspected source of the Covid-19 virus.
The team of experts from WHO and China said in February the virus which causes Covid-19 – SarS-CoV-2 is “extremely unlikely” to have entered the human population as a result of a laboratory-related incident.
But as the report was published, Dr Tedros Adhanom Ghebreyesus director general of the WHO, said: “The team visited several laboratories in Wuhan and considered the possibility that the virus entered the human population as a result of a laboratory incident.
“However, I do not believe that this assessment was extensive enough.
“Further data and studies will be needed to reach more robust conclusions.
“Although the team has concluded that a laboratory leak is the least likely hypothesis, this requires further investigation, potentially with additional missions involving specialist experts, which I am ready to deploy.
“Let me say clearly that as far as WHO is concerned all hypotheses remain on the table.”
Investigators looked at four hypotheses when examining the possible origins of the virus:
– Direct transmission from an animal species into the human population.
– The introduction of the virus from an intermediary host species through another animal species “potentially closer to humans” where the virus could adapt, circulate and then jump to humans.
– The food chain, in particular the potential for frozen products acting as a “surface” for the transmission of the virus.
– A lab-related incident.
The report concluded that the introduction of the virus from an intermediate host is the most likely scenario – which means the virus “jumped” from one species to another, and then jumped from the second species to humans.
It also suggests that the virus was circulating for several weeks before it was initially detected.
The authors wrote: “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.”
Dr Tedros added: “This report is a very important beginning, but it is not the end. We have not yet found the source of the virus, and we must continue to follow the science and leave no stone unturned as we do.
“Finding the origin of a virus takes time and we owe it to the world to find the source so we can collectively take steps to reduce the risk of this happening again. No single research trip can provide all the answers.”
Since the virus was first detected in December 2019, there have been more than 127 million cases around the globe and 2.8 million deaths.