Covid origin: Why the Wuhan lab-leak theory is so disputed

More than three years after Covid-19 was detected in the Chinese city of Wuhan, the question of how the virus first emerged remains a mystery.

But on 28 February 2023 the controversial claim that the pandemic might have leaked from a Chinese laboratory - once dismissed by many as a fringe conspiracy theory - resurfaced with FBI Director Christopher Wray's comments that the bureau believes Covid-19 "most likely" originated in a "Chinese government-controlled lab".

It is the first public confirmation of the FBI's classified judgement of how the pandemic virus...