Beijing has never fully co-operated with international investigators, impeding the search for a definitive answer. But scientists continue their quest to establish the causes of a global health crisis that killed millions of people, caused trillions of dollars of economic damage and increased fears over the risks of virus research.

Ex-CNN editor Chris Cilizza conceded on Monday that he "screwed up" in his assessment of the lab leak theory, suggesting that President Trump was likely right about COVID's origins.

The CIA says both a natural origin and a lab leak "remain plausible" as potential sources of covid-19, following a review of the pandemic's origins.

The intelligence agency says it has a “low confidence” in its new finding, but this is further than it has ever gone in pinpointing the origin of a virus that killed millions worldwide.

The CIA now assesses the virus that causes Covid-19 more likely originated from an accidental lab leak in China, rather than occurring naturally, according to a statement from the agency Saturday, just days after Director John Ratcliffe took the reins.

Langley joins the FBI and Energy Department in agreeing that a lab leak is the most likely source of the pandemic.

CIA continues to assess that both research-related and natural origin scenarios of the COVID-19 pandemic remain plausible.”

The Central Intelligence Agency said the Covid-19 pandemic “more likely” originated from a lab leak than a natural source, shifting its stance after previously saying both scenarios were possible.

It was unclear the extent to which the agency has collected new intelligence on COVID-19's origins and whether that new evidence was used to formulate the latest assessment.