Scientists and disease experts say the Wuhan coronavirus outbreak could soon be declared a pandemic.

The World Health Organisation last week designated the coronavirus – whose scientific name is 2019-nCoV – a "public-health emergency of international concern."

Calling the virus a pandemic would take it to a new level, however, since that term refers to a more global outbreak.

The coronavirus is "very, very transmissible, and it almost certainly is going to be a pandemic," Anthony Fauci, the director of the US's National Institute of Allergy and Infectious Diseases, told The New York Times on Sunday.

Here are criteria for a virus to be labelled a pandemic:

The WHO defines a pandemic as "the worldwide spread of a new disease."
A pandemic disease spreads across "several countries or continents, usually affecting a large number of people," according to the US Centres for Disease Control and Prevention.
A viral outbreak could be characterised as a pandemic if it is "markedly different from recently circulating strains" and if "humans have little or no immunity" to it, according to the UK's Health and Safety Executive.
A disease becomes a pandemic when it can infect many people over a large area, be transferred from person to person, and cause clinical illness, the HSE said.