Twelve patients treated by two British GPs who have been diagnosed with coronavirus are being traced by health officials, the BBC understands.
Between them, the two doctors worked in four different places in East and West Sussex – a nursing home, an A&E department and two GP practices.
A British man linked to 11 cases of coronavirus has now left hospital and returned home.
NHS England said Steve Walsh posed “no risk to the public”.
Mr Walsh, 53, from Hove, said he was happy to be home and feeling well.
“I want to give a big thank you to the NHS who have been great throughout, and my thoughts are with everyone around the world who continues to be affected by the virus,” he said.
“It’s good to be back with my family and I would ask you please to respect our privacy from this point on.”
Mr Walsh had mild symptoms and was discharged from a specialist infectious diseases unit at Guy’s and St Thomas’ NHS Foundation Trust in London after making a full recovery.
He was infected by the new coronavirus after attending a business conference in Singapore in January.
A total of 1,750 people have now tested negative for the new virus in the UK, with eight positive.
The two Brighton GPs with coronavirus, who stayed in the same ski chalet in France as Mr Walsh, are now in isolation and efforts to trace the 12 patients they came into contact with them are ongoing.
The GP practices in Brighton where they worked have now reopened after a deep clean.
Worthing Hospital, where one of the GPs worked a shift in A&E, continues to operate as normal, a Department of Health spokeswoman said.
A Brighton nursing home – Patcham Nursing Home – has closed to visitors as a precaution, but nobody there is reported to be unwell.
One of the Brighton doctors has been named as Catriona Greenwood. The second GP has not been named.
On Tuesday, the World Health Organization said the official name for the disease caused by the coronavirus is Covid-19.
Prof Neil Ferguson, infectious disease expert from Imperial College London, told the BBC that he thought new cases of the virus could still rise.
“I think we’re in the early phases of a global pandemic at the moment,” he said.
Prof Ferguson added it was likely that only one in three cases coming into the UK was being picked up.
But John Oxford, emeritus professor of virology at Queen Mary University London, said he thought the virus had a weakness – and people’s actions could help slow transmission.
“It’s not about wearing a mask – it’s less of the hand-shaking, touching and kissing,” he said, speaking on the Today programme.
What are the symptoms of coronavirus and what can help stop its spread?
The main signs of infection are fever (high temperature) and a cough as well as shortness of breath and breathing difficulties.
Frequent hand washing with soap or gel, avoiding close contact with people who are ill and not touching your eyes, nose and mouth with unwashed hands, can help cut the risk of infection.
Catching coughs and sneezes in a tissue, binning it and washing your hands can minimise the risk of spreading disease.
Anyone experiencing symptoms, even if mild, after travelling from mainland China, Thailand, Japan, Republic of Korea, Hong Kong, Taiwan, Singapore, Malaysia or Macau, is advised to stay indoors and call the NHS 111 phone service.
On Monday, the government issued new powers in England to keep people in quarantine to stop the virus spreading.
Under the Department of Health measures, people will not be free to leave quarantine and can be forcibly sent into isolation if they pose a threat.
The BBC understands that two prisoners on a wing at HMP Bullingdon in Oxfordshire have been tested for the virus. One of them, a remand prisoner, had recently returned to the UK from Thailand.
The overall number of infections is more than 44,000 on mainland China, with cases in more than 20 countries.
On Wednesday, around 300 employees were evacuated from Singapore’s biggest bank, DBS, after one person fell ill with the virus.
The Chinese Grand Prix – which had been scheduled for 19 April in Shanghai – has been postponed as a result of the outbreak.
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