The theory that COVID-19 originated from a laboratory in Wuhan has not been dismissed by investigators, the head of the World Health Organisation has suggested.
Earlier this week, a WHO-led mission in China said it was not looking further into the question of whether the virus escaped from a lab, which it considered highly unlikely.
However, in a press briefing on Friday, director general Tedros Adhanom Ghebreyesus said: “Some questions have been raised as to whether some hypotheses have been discarded.
“Having spoken with some members of the team, I wish to confirm that all hypotheses remain open and require further analysis and study.
“Some of that work may lie outside the remit and scope of this mission.
“We have always said that this mission would not find all the answers, but it has added important information that takes us closer to understanding the origins of the COVID-19 virus.”
The WHO mission leader, Dr Peter Ben Embarek, said on Friday the labs in Wuhan his team visited stated they had not been working with the virus that causes COVID-19, or had it in their collections before the outbreak.
Mr Embarek said it was possible the virus could still be present in samples that have not yet been analysed.
He added that if scientists from Wuhan labs had been studying the virus before the outbreak, it would not have been a secret.
“Usually laboratory researchers who work and discover new viruses would immediately publish their findings. That’s a common practice around the world, particularly with new, interesting viruses,” he said.
He said his team had gained a much better insight into the early stages of the outbreak and concluded there was no large cluster of the disease in Wuhan or elsewhere around the city in the months prior to the first cases in December 2019.
The mission has said its main hypothesis is that the virus originated in a bat, although there are several possible scenarios for how it passed to humans, possibly first by infecting another animal species.
The former administration of US president Donald Trump said it believed the virus may have escaped from a lab in Wuhan.
China has strongly denied this, and says the Wuhan Institute of Virology was not studying related viruses.