Out of an abundance of caution, we temporarily suspended the account of the driver who transported the individual to the hospital, and we remain in close contact with Public Health England (PHE)".
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.
She added: "I'm feeling completely well but to be extra-cautious I'm cancelling my public engagements until 20th February".
United Airlines said in a statement: "Our team at London Heathrow Airport is providing assistance related to United flight 901 (San Francisco-London Heathrow) today, following reports of an individual becoming unwell onboard".
Heathrow Airport declined to comment on reports other planes were also held due to coronavirus fears.
Lewisham hospital on Thursday confirmed the unnamed patient had not followed public health officials' advice and had simply "self-presented" at its A&E unit last Sunday afternoon.
During a press conference on Tuesday, WHO director-general Tedros Adhanom Ghebreyesus said China's effort to contain the virus was the reason there have been so few worldwide cases.
Passenger Neerag Malhotra tweeted that passengers were stuck "waiting for doctor confirmation" and that the affected person was "isolated at the back of the plane".
Two staff from Lewisham Hospital in south London are now in isolation at home after coming into contact with the woman.
On Wednesday, the Department of Health and Social Care confirmed a patient was being treated at a hospital in London, bringing the number of cases in the United Kingdom to nine.
No other patients were exposed to the risk of infection by the manner of her arrival, the hospital said. On Wednesday she was taken to another London hospital, St Thomas', for treatment. "We were told to stay [seated] until authorities came on board, and [the captain] said that seven other flights had landed and had a similar situation".
This comes after a Chinese woman, who lives in London with relatives, and is in her late 20s or early 30s, was tested positive for coronavirus. Two of those are Britons, taking the number of Britons on the ship diagnosed with coronavirus to three.