Health officials have contacted hundreds of people who attended a conference in London, after it emerged someone subsequently diagnosed with coronavirus had been there.
The person, who has not been identified, was at the UK Bus Summit at the QEII Conference Centre last week.
Dr Yimmy Chow from Public Health England said the delegates had been informed as a precaution.
So far, nine people in the UK have been diagnosed with the virus, Covid-19.
Around 250 people from the bus and transport industry were listed as attending the annual summit on 6 February in Westminster.
Among them was the Labour MP for Nottingham South, Lilian Greenwood, who is a former chair of the transport select committee and who spoke at the conference.