Members of a World Health Organisation-led team looking for clues about the origins of Covid-19 are holding a briefing after nearly a month of meetings and site visits in the Chinese city of Wuhan, where the disease was first identified.
The WHO said the briefing would also include experts from the Chinese side who have been involved in the investigation.
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”.
Another team member, 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.
Liang Wannian, head of the expert Covid-19 panel at China’s National Health Commission, is also attending. He told the briefing that research must focus on how the virus circulated in animals before infecting humans.
A virus capable of causing a pandemic must already be adapted to human contact, he says.
Prof Liang says the discovery of the virus suggests Sars-Cov-2 (the official designation of Covid-19) may have originated from zoonotic (an infectious disease that jumps from an animal to a human) transmission but an animal host remains to be identified.
Bats and pangolins are potential candidates for transmission but coronavirus samples found in those species are not identical to Sars-Cov-2, he adds.
The high susceptibility of minks and cats to Sars-Cov-2 suggests there may be other animals that serve as reservoirs, but research is insufficient, Prof Liang says.