Riot police were used to quell protests in Hong Kong overnight as the death toll from the new coronavirus rose to 81.A homemade bomb exploded at a hospital in Hong Kong, where protesters also set fire to a housing block that had been earmarked as a quarantine facility, Reuters reported.The device exploded in a toilet cubicle at the Caritas Medical Centre and caused the temporary evacuation of some patients but no one was hurt.Protesters threw petrol bombs at the empty housing complex while riot police moved in with tear gas.Chinese officials said the new coronavirus is infectious in its incubation period before symptoms show, making it more difficult to contain. The country’s health minister admitted the virus is “getting stronger”.China’s National Health Commission said the death toll from the coronavirus has risen to 81 – there were 769 new cases confirmed on Sunday, bringing the total number of infected to 2,827.The government also reported five cases in Hong Kong and two in Macau.(PA)Other cases have also been found in Thailand, Taiwan, Japan, South Korea, the US, Vietnam, Singapore, Malaysia, Nepal, France, Canada and Australia.Read more:Coronavirus outbreak: What are the symptoms?What the coronavirus means for the economyHow is the international media reacting to the coronavirus?The Department of Health and Social Care said 73 people across England, Wales, Scotland and Northern Ireland have been tested for the deadly flu-like virus, but all have returned negative.The current risk to the public remains low, the department said, adding that the government is continuing to monitor the situation closely.But England’s chief medical officer Professor Chris Whitty said there was a “fair chance” cases would emerge in Britain.Police disperse Hong Kong protestors during unrest at the spread of the coronavirus (Picture: Getty)One medical expert said it is “likely” the coronavirus will be confirmed in the UK in the next few weeks.Britons trapped in the Chinese province at the centre of the outbreak have been urged to leave the area if they are able to do so.The Foreign Office updated its guidance to “advise against all travel to Hubei province”, which has been on lockdown for several days as China seeks to contain the illness.But the guidance also added: “If you are in this area and able to leave, you should do so. This is due to the ongoing novel coronavirus outbreak.”Chinese president Xi Jinping called the outbreak a grave situation and said the government was stepping up efforts to restrict travel and public gatherings.A medical official takes the temperature of a man at the departure hall of the airport in Changsha, Hunan Province, China. (Reuters)The spread of the coronavirus has come at China’s busiest travel period of the year, when millions crisscross the country or head abroad for the Lunar New Year holiday.Chinese travel agencies have been told to halt all group tours, and concern is growing over the potential impact of millions of people travelling back to the cities after the Lunar New Year holiday ends on Thursday.The National Health Commission said anyone travelling from Wuhan is now required to register with community health stations and quarantine themselves at home for 14 days – the virus’s maximum incubation period.China cut off trains, planes and other links to the city on 22 January and has steadily expanded the lockdown to 16 surrounding cities with a combined population of more than 50m.Wuhan is building two makeshift hospitals with about 1,000 beds each to handle patients.