A coronavirus expert has warned fake news spread online can lead to bad medical advice and people taking "greater risks" during disease outbreaks.

Professor Paul Hunter, of the University of East Anglia's (UEA) Norwich Medical School, said people were more likely to spread "bad advice" than they were trusted guidelines from the NHS, Public Health England, or the World Health Organisation.

“Misinformation means that bad advice can circulate very quickly – and it can change human behaviour to take greater risks," he said.

“Examples of risky behaviour during infectious disease outbreaks include not washing hands, sharing food with ill people, not disinfecting potentially contaminated surfaces, and failing to self-isolate."

More than 5,000 new cases were diagnosed on Thursday in China. Credit: PA

It comes as the death toll from the coronavirus outbreak in China hit 1,380 on Friday, while the number of infected jumped up by 5,090 to 63,581.

China's health commission said the jump was affected by a change in reporting procedures, when cases are now counted based on a doctor's diagnosis and before they have been confirmed by laboratory analysis.

Professor Hunter, who ran tests with colleague Julii Brainard, said speculation was rife online about the origin of the virus and how it is spread.

"Worryingly, research has shown that nearly 40% of the British public believe at least one conspiracy theory, and even more in the US and other countries," he said.

Health centres in London have begun distributing 'coronavirus alert' signs. Credit: PA

Sir Simon Stevens, chief executive of the NHS, said on Thursday that many more people in the UK may need to self-isolate to contain the illness, which has been officially named Covid-19.

More than 80 people quarantined at Arrowe Park Hospital on the Wirral were allowed to leave following 14 days in isolation after it was ruled they posed "no risk to the public".

Stevens said the group had been "highly responsible, pragmatic and stoical" and "set an important example."

A medical centre in Brighton closed after a staff member was diagnosed with the virus. Credit: PA

The Department of Health said on Thursday that 2,521 people in the UK have been tested, of whom 2,512 were confirmed negative and nine positive.

A total of 218 people on quarantined cruise ship the Diamond Princess in Japan have tested positive for Covid-19 disease. Three of those are Britons

Cruise ship Diamond Princess has been quarantined off Japan. Credit: AP

More than 3,500 passengers and crew are onboard the ship, with health officials testing older and medically vulnerable passengers first for the coronavirus.

If found to be the negative, the passengers have the option to be taken off the quarantined ship and placed in temporary accommodation on land.

Japan also confirmed its first death from the virus on Thursday.