A joint WHO-China study on the origins of Covid-19 says that transmission of the virus from bats to humans through another animal is the most likely scenario and that a lab leak is “extremely unlikely”, the Associated Press (AP) reported on Monday.

The findings were largely as expected and left many questions unanswered, and the team proposed further research in every area except the lab leak hypothesis, the report added, citing a draft copy obtained by the Associated Press.

As per the AP report, the joint study report is being closely watched since discovering the origins of the virus could help scientists prevent future pandemics — but it’s also extremely sensitive since China bristles at any suggestion that it is to blame for the current one. 

Repeated delays in the report’s release have raised questions about whether the Chinese side was trying to skew its conclusions.

The AP report stated that the researchers, in the draft copy of the study, had listed four scenarios in order of likelihood for the emergence of the coronavirus named SARS-CoV-2. 

Topping the list was transmission from bats through another animal, which they said was likely to very likely. They evaluated direct spread from bats to humans as likely, and said that spread through “cold-chain” food products was possible but not likely.

However, the report, according to AP, says that “the evolutionary distance between these bat viruses and SARS-CoV-2 is estimated to be several decades, suggesting a missing link.”

It said highly similar viruses have been found in pangolins, which are another kind of mammal, but also noted that mink and cats are susceptible to the Covid-19 virus, suggesting they could be carriers, too.