The UK is to monitor flights arriving from China, as part of a series of precautionary measures after the spread of a new coronavirus.
The measures, announced by the Department of Health, will apply to flights from Wuhan to London Heathrow.
The flights will be met in an isolated part of Terminal 4, with a health team available to check for symptoms.
Public Health England said the current risk to the UK has been changed from "very low" to "low".
The health team will check for symptoms of coronavirus and provide information to all passengers about symptoms.
Meanwhile, the Foreign Office advised against all but essential travel to Wuhan.
The first flight to arrive in the UK after the measures were announced landed just after 18:00 GMT.
A spokesman for Heathrow said the airport was working with the government to "support the implementation of the measures".
He added: "We would like to reassure passengers that the government assesses the risk of a traveller contracting coronavirus to be low."
In Geneva, the World Health Organization's emergency committee is meeting on Thursday to assess the global risks posed by the virus and decide if it should be declared an international public health emergency - as happened with swine flu and Ebola.
Wuhan, the city at the heart of the outbreak, is to temporarily shut public transport in an attempt to halt the spread of the virus.
The airport and train stations and other modes of transport will be closed to outgoing passengers from 10:00 local time on Thursday.
There are estimated to have been 4,000 cases of the virus since the outbreak began, according to Professor Neil Ferguson, director of the Medical Research Centre for Global Infectious Disease Analysis.
However he said it was difficult to assess the numbers and Chinese hospitals would probably now be overwhelmed with suspected cases.
The outbreak has killed 17 people, and there are more than 500 confirmed cases.
The vast majority of cases have been in Wuhan and Chinese authorities believe the virus originated from a seafood market that "conducted illegal transactions of wild animals".
However it has also spread to other Chinese cities and a handful of cases have been identified abroad, including in Japan and the US. There have been no cases in Britain.
On Tuesday, authorities in China confirmed for the first time that human-to-human transmission of the virus had taken place.
Health team at airport
On Wednesday, the Department of Health announced there will be an "enhanced monitoring" package in place for all direct flights from China to the UK because of the threat of coronavirus.
In a statement, the government said the measures will include:
- A health team to meet each direct flight from Wuhan to London Heathrow
- Passengers on flights will hear an announcement and be given a leaflet to encourage them to report if they are ill
- Aircraft will land in an isolated area of Heathrow Terminal 4 that "better lends itself to any health contingencies"
There are currently three direct flights a week from Wuhan to London Heathrow.
The monitoring of direct flights will be kept "under continuous review" and expanded to other Chinese departure points if necessary, the government added.
Individuals "should seek medical attention if they develop respiratory symptoms within 14 days of visiting Wuhan, either in China or on their return to the UK", according to Dr Nick Phin, deputy director of Public Health England's National Infection Service.
He added: "They should phone ahead before attending any health services and mention their recent travel to the city."
Dr Nathalie MacDermott, a clinical lecturer at King's College London, said screening for symptoms at the airport was "limited" as it will only identify people who have symptoms at the point they transit through the airport.
"It is therefore important that Public Health England are able to trace [travellers] in the future to determine if they have gone on to develop any symptoms," she said.
Earlier, Transport Secretary Grant Shapps told BBC Radio 5live said it was important to "stay ahead of the issue" and monitor the situation very carefully.
Screening stepped up
Professor Calum Semple, an expert in outbreak medicine at Alder Hey Children's Hospital, said it could be difficult to spot passengers infected with the virus because it takes about five days for symptoms to appear and during this initial period someone could seem completely healthy.
He told the BBC that these symptoms, which include fever, cough, shortness of breath and breathing difficulties, can also be difficult to differentiate from seasonal flu.
It comes as authorities in several countries, including Australia, Singapore, Hong Kong, Taiwan and Japan have stepped up screening of air passengers from Wuhan.
US authorities last week announced similar measures at airports in San Francisco, Los Angeles and New York.
They have now announced plans to introduce similar measures at airports in Chicago and Atlanta this week.
What we know so far about the Chinese coronavirus
This type of coronavirus is a new strain that hasn't been seen in humans before, which means doctors still have lots to learn about it.
The first human cases were identified in the Chinese city of Wuhan in December 2019. There have not been any other suspected human cases reported prior to this.
The incubation period (how long it takes for symptoms to appear after catching the infection) is days, rather than weeks.
It is not yet known how or when the virus became infectious to people. Experts believe the first cases were transmitted by an animal.
Other coronaviruses, such as Sars and Mers, came from civet cats and camels respectively.
At the moment, there is no vaccine that can protect people against it, but researchers are looking to develop one.
The UK's expected measures do not appear to include a medical screening of passengers at the airport for signs of the virus, as the UK did in 2014 following the Ebola outbreak.
Then, screening involved taking people's temperatures to check whether they have a fever and asking several questions to assess their risk.
China - which is stepping up containment measures - has still not been able to confirm the exact source of the virus.
But the country's National Health Commission vice-minister Li Bin said there was evidence that the disease was "mainly transmitted through the respiratory tract".
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