World Health Organization (WHO) completed its 28-day mission to the Chinese city of Wuhan this week seeking clues about the origins of COVID-19.The following looks at their findings.What are the main scenarios?Peter Ben Embarek, the WHO's leading animal disease expert, said the team conducted scientific investigations into four main scenarios about how SARS-CoV-2, the virus that causes COVID-19, spread into humans.In the first, a single person was exposed to SARS-CoV-2 through direct contact with the host species, the horseshoe bat.
The virus could have been circulating in humans for a while before making its breakthrough in heavily populated Wuhan.The second scenario, seen as the most likely, involves transmission to humans via an as yet.