His executive order targeted the elimination of what is called gain-of-function, which studies how viruses become more powerful. The United States funded that sort of research at the Wuhan lab, in the city where the initial outbreak was reported. But a competing theory is that a person somehow came into contact with an infected animal.

The former President's executive order will immediately halt "any present and all future" US funding for gain-of-function research in countries like China and Iran that lack proper safety oversight

US President Donald Trump has signed an executive order banning US-funded virus research amid arguments between America and China about the origin of Covid.