Wuhan lab leak theory: How Fort Detrick became a centre for Chinese conspiracies

A disinformation campaign claiming that the Covid-19 virus originated from an American military base in Maryland has gained popularity in China ahead of the release of a US intelligence report on the virus origins.

In May, US president Joe Biden ordered a 90-day probe into whether the Covid-19 virus came from a lab accident or emerged from human contact with an infected animal.

Until then, the "Wuhan lab leak" theory had been dismissed by most scientists as a fringe conspiracy theory.

But now as the report is due to be released, China has gone on the offensive. In the past few weeks, Chinese sources have been amplifying a baseless claim that Covid-19 was made in the US.

Using everything from rap music to fake Facebook posts, experts say the propaganda efforts have been successful at convincing the domestic Chinese audience to cast scepticism on international criticism of the country's role in the Covid-19 pandemic. But, experts say, it has done little to legitimise China to the outside world.