Members of an international team that wrote a study into the origins of COVID-19 with Chinese colleagues say it is only a "first start" and more needs to be done.

They appealed for patience as reams of information continues to pour in. The team emphasized that hypotheses, including a possible laboratory leak theory, cannot be fully ruled out.

Team leader Peter Ben Embarek of the World Health Organization says its members remain "open-minded" as it formally presented its long-awaited first-phase look into the possible outbreak the coronavirus. The virus has left nearly 2.8 million people dead and damaged economies and livelihoods since it first emerged in China.

Ben Embarek says international team members faced political pressure from "all sides," but insisted "We were never pressured to remove critical elements in our report." He also pointed to "privacy" issues in China that prevented sharing of some data, saying such restrictions would exist in many countries.

Joined by several other members of the 17-member international team for a news conference, Ben Embarek says, "where we did not have full access to all the raw data we wanted, that has been put as a recommendation for the future studies."

Ben Embarek says it was difficult to know when -- if at all -- the exact origin of the pandemic will come to light. He says one hypothesis, pushed hard by the Trump administration, that the virus may have leaked from a laboratory wasn't likely, but "not impossible" either.