A British man who contracted coronavirus in Singapore appears to be linked to at least 11 other cases, prompting fears he could be a so-called "superspreader" - but what does it mean?
What is a superspreader?
A person who has a disproportionately higher ability to infect others with a virus.
Many outbreaks in the past have been found to follow the 20:80 rule, with about 20% of individuals contributing to 80% of the disease's spread.
Identifying them is vital to keep an outbreak under control.
It is unclear why a person can be a superspreader.
It's been suggested some people may "shed" more of the virus into the environment (eg when they cough or sneeze) because of how their immune system works.
A person's behaviour may also contribute to them becoming a superspreader.
For instance, someone who travels a lot and has contact with many people - such as an international business executive - could spread the virus to multiple people.
This appears to be the case with the British businessman - who travelled from Singapore to the French Alps and back to the UK, and is being linked to multiple cases.
Another suspected superspreader in the current outbreak is a man believed to have infected 14 workers at a hospital in Wuhan, China.
Scientists in China have found the new coronavirus can have an incubation period of up to 24 days - although currently the World Heath Organisation estimates the incubation period to be up to 14 days.
The superspreader phenomenon was also identified in the SARS outbreak in 2002-2004.
One famous case from history is "Typhoid Mary" - an Irish cook who infected 51 people in the US at the start of the last century.
How did British man spread the virus?
20-23 January - UK businessman attends conference at a five-star Singapore hotel organised by UK gas analytics company Servomex.
24 January - Flies to Contamines-Montjoie ski resort in the Haute-Savoie area of the French Alps.
28 January - Takes the 6.50pm easyJet fight from Geneva in Switzerland to London Gatwick.
The airline says all passengers seated near the man will be contacted, but that the risk is "very low".
6 February - Man diagnosed with the virus at a Brighton hospital and later transferred to Guy's and St Thomas' Hospital in London.
He becomes the UK's third case after two people diagnosed in York.
Before his diagnosis he visited The Grenadier pub in Hove - but health officials have said there is "minimal ongoing risk of infection to either guests or staff."
8 February - Five Britons who were in a ski chalet with him test positive - including a nine-year-old. A group of 11 from the UK were sharing the chalet.
They are not in a serious condition
9 February - Another British man - who was also in the ski resort - tests positive in Majorca. His wife and two daughters test negative.
9/10 February - Five more people are diagnosed with the virus by UK officials.
They are also understood to have come into contact with the man in the French ski resort - although it's not clear if they were staying in the chalet.
It brings the total confirmed cases in the UK to eight.
A Brighton medical surgery also closes after it is linked to one of the newly diagnosed cases.