International experts investigating the origins of Covid-19 have all but dismissed a theory that the virus came from a laboratory in China.
Members of a World Health Organisation-led team held a briefing after nearly a month of meetings and site visits in the Chinese city of Wuhan, where the disease was first identified.
Watch the full briefing:
The team arrived in Wuhan on 14 January and after two weeks of quarantine, visited key sites like the Huanan seafood market, the location of the first known cluster of infections, as well as the Wuhan Institute of Virology, which has been involved in coronavirus research.
Members of the team have sought to rein in expectations about the mission, with zoologist Peter Daszak telling Reuters last week that one of their aims was to "identify the next steps to fill in the gaps".
Team leader Peter Ben Embarek. Photo: AFP
Embarek told the briefing that its investigation had uncovered new information but had not dramatically changed the picture of the outbreak.
He said that work to identify the origins of the coronavirus points to a natural reservoir in bats, but it was unlikely that this happened in Wuhan.
He said identifying the animal pathway remained a "work in progress", but that it was "most likely" to have crossed over to humans from an intermediary species.
The experts also said there was "no indication" that the virus was circulating in Wuhan before the first official cases were recorded there in December 2019.
Embarek also said that the hypothesis leaked from a laboratory is an extremely unlikely pathway for Covid-19 and will not require further study as part of their work in studying the origins of the virus.
The virus that causes Covid-19 could have been circulating in other regions before it was identified in the central Chinese city of Wuhan at the end of 2019, Liang Wannian, an expert with China's Health Commission told the briefing.
He said that there had been no substantial spread of the virus in the city before the late 2019 outbreak.
He said more work was needed to identify the source of the virus.
Prof Liang said a virus that is capable of causing a pandemic must already be somehow adapted to human contact, so research should focus on potential virus transmission between animals.
Bats and pangolins are potential animal sources of the virus, Professor Liang said, but the coronavirus samples found in them were similar, but not identical to the virus found in humans.
Professor Liang also said because cats and minks are so susceptible to the coronavirus, there is a suspicion that other animals are also catching and passing on the virus.
Another team member in the WHO delegation, infectious disease expert Dominic Dwyer, said it would probably take years to fully understand the origins of Covid-19.
The United States said China needed to be more open when it comes to sharing data and samples as well as allowing access to patients, medical staff and lab workers. Beijing subsequently accused Washington of politicising a scientific mission.
-Reuters / ABC / BBC