Chinese authorities and experts are at odds about the origin of the ongoing coronavirus outbreak. More specifically, who is "patient zero" for the outbreak. Also known as an index case, patient zero is a term used to describe the first human infected by a viral or bacterial disease in an outbreak.

Advances in genetic analysis now make it possible to trace back the lineage of a virus through those it has infected. Combined with epidemiological studies, scientists can pinpoint individuals who may have been the first people to start spreading the disease and so trigger the outbreak.

Identifying who these people are can help address crucial questions about how, when and why it started. These can then help to prevent more people from getting infected now or in future outbreaks.

Do we know who patient zero is in the Covid-19 coronavirus outbreak that started in China?

The short answer is – no.

Chinese authorities originally reported that the first coronavirus case was on 31 December and many of the first cases of the pneumonia-like infection were immediately connected to a seafood and animal market in Wuhan, in the Hubei province.

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This region is the epicentre of the outbreak, with almost 82% of the 75,000-plus cases registered so far in China and globally are from here, according to statistics complied by Johns Hopkins University. (Read more about the global fight against coronavirus.)