Limited human-to-human transmission of a new coronavirus in China may have taken place within families, and there could be a wider outbreak that affects other countries, the WHO has warned.

Coronaviruses are a large family of viruses that can cause infections, ranging from the common cold to SARS.

A Chinese woman has been quarantined in Thailand with a mystery strain of coronavirus, Thai authorities said earlier in the week — the first time the virus has been detected outside China.

In all, 41 cases of pneumonia have been reported in the central Chinese city of Wuhan, which preliminary lab tests cited by state media showed could be from a new type of coronavirus.