Origin story: what do we know now about where coronavirus came from?

When Chinese scientists alerted colleagues to a new virus last December, suspicion fell on a Wuhan market. What have health officials learned since then?

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Maria van Kerkhove was staying with her sister in the US for the Christmas holidays, but checking her emails. As always. Every day there are signals of potential trouble, said the World Health Organization virologist who was to become a household name and face within weeks.

There's always something that happens at Christmas time. There's always some alert, or a signal of a suspected case. The last several years it's been Mers [Middle East respiratory syndrome] - a suspect case travelling to Malaysia or Indonesia or Korea or somewhere in Asia from the Middle East. So there's always some kind of signal. There's always something that happens," she said.