Origins: Hunting the Source of Covid-19

It remains one of the world's biggest mysteries: what triggered the Covid-19 pandemic? The BBC's global health correspondent Tulip Mazumdar hears from two of the scientists who were on the controversial China/WHO mission to Wuhan at the start of the year, as well as experts who have investigated outbreaks of new diseases before. Tulip delves into the main theories, and looks at why a hypothesis about a possible accidental lab leak is now being taken much more seriously.