WITH the 20th positive diagnosis of coronavirus in the UK, London commuters are donning protective masks on public transport.
Photos of tourists, residents and workers on buses and the Tube show people covering their noses and mouths, as the risk of a global spread of the killer bug is now "very high".
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As of tonight, there are 18 infected people in England, one in Northern Ireland and one in Wales.
And a patient diagnosed with coronavirus in Surrey has become the first to catch the illness within the UK, health bosses have confirmed tonight.
Chief medical officer Professor Chris Whitty said: "It is not yet clear whether they contracted it directly or indirectly from an individual who had recently returned from abroad.
"This is being investigated and contact tracing has begun.
"The patient has been transferred to a specialist NHS infection centre at Guy's and St Thomas'."
Jonathan Ball, professor of molecular virology at the University of Nottingham, said UK transmission was "always a real possibility".
He added that, with symptoms very similar to flu, it could be easy for Covid-19 to go under the radar.
Prof Ball said: "This case - a person testing positive for novel coronavirus with no known link to an affected area or known case - marks a new chapter for the UK.
"And it will be crucial to understand where the infection came from to try to prevent more extensive spread.
"This was always a concern - this is a virus that frequently causes symptoms very similar to mild flu or a common cold, and it's easily transmitted from person to person."
Dr Michael Head, senior research fellow in global health at the University of Southampton, said it was "unsurprising" to see a case of human-to-human transmission in the UK.
He added: "There will be significant efforts to look at how this patient came to be infected, who is the index case in the UK and to see if any there are any other secondary cases.
"Though this is a notable development here in the UK, the overall risks to the public right now remain unchanged."
Dr Alison Barnett, centre director for Public Health England (PHE) said tonight that a Surrey resident was the latest person to contract the virus.
She said health officials are trying to track down those who had been in close proximity with the infected person "to help reduce the risk of further cases.
"Close contacts will be given health advice about symptoms and emergency contact details to use if they become unwell in the 14 days after contact with the confirmed case."
In Surrey, Haslemere Health Centre was closed today, with a statement on its website saying: "The surgery is temporarily closed today to enable a clean of the surgery as a routine precautionary measure.
"The practice will reopen on Saturday and patients will be advised if their appointment needs to be rearranged."
Surrey county council's interim director of public health Ruth Hutchinson said the authority, "is working with health colleagues to do everything we can to stop the virus spreading and ensure the people of Surrey are protected".
News of the 20th coronavirus patient comes after a British man became the first UK citizen to die from the killer bug.
The man, who was on board the Diamond Princess cruise ship, was the sixth person from the vessel, which has been quarantined off the Japan's coast amid the global outbreak, to have died.
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The risk of a global spread and impact of the coronavirus is now "very high", the highest level of alarm, but containment is still possible, the World Health Organization (WHO) said on Friday.
While there's no vaccine, plenty of researchers are working on one.
The best way to prevent infection is hand washing, cleaning surfaces with regular household sprays and wipes, and avoiding close contact with people who are sick.
The virus spreads mostly through droplets from coughs and sneezes.