The decision to delay closing schools and introduce other strict measures to combat coronavirus has been defended by England's deputy chief medical officer.
Dr Jenny Harries said experts are assessing new cases on an hourly basis to achieve a "balanced response".
It comes as a man in his early 80s became the sixth person with the virus to die in the UK.
Meanwhile, many airlines cut thousands of flights, including to and from Italy, in the wake of the outbreak.
According to the latest figures, there were 373 confirmed cases as of 09:00 GMT on Tuesday. Of them, 324 are in England.
The latest death happened on Monday evening and was a man with underlying health conditions who was being looked after at Watford General Hospital, the West Hertfordshire Hospitals NHS Trust said.
He caught the virus in the UK and officials are trying to trace who he was in contact with, the country's chief medical adviser Prof Chris Whitty said.
Earlier, Dr Harries said the vast majority of those diagnosed with coronavirus in Britain are "pretty well" but that they may "feel a bit rough for a few days".
She told BBC Breakfast new government measures could follow as UK cases begin to rise rapidly over the next two weeks.
She added that people with flu-like symptoms will be advised to self-isolate within 10 to 14 days and, at the same time, significant increases in the number of cases are likely to begin.
Dr Harries said cancelling big outdoor events like football matches would not necessarily be a decision supported by science.
"The virus will not survive very long outside," she said. "Many outdoor events, particularly, are relatively safe."
In other developments:
- The UK Foreign Office warned Britons against all but essential travel to Italy after the country extended its coronavirus measures, including travel restrictions
- Italian tourists have been told to self-isolate on arrival in Britain as several UK airlines cancelled flights to and from Italian airports
- The owner of Nottingham Forest FC, Evangelos Marinakis, has tested positive after returning from Greece
- Royal Bank of Scotland said it would allow customers to defer mortgage payments if needed
- The NHS partnered with technology firms to help promote official health advice online
- And new research showed that, on average, it took five days for people to show symptoms of the virus
Italy's extended quarantine measures require residents to stay home, seek permission for essential travel, and justify leaving the country.
Son speaks of father's death
On Sunday, a 60-year-old man from Greater Manchester became the third person to die after contracting coronavirus after recently visiting northern Italy.
The son said his father fell ill "instantly" after returning to the UK at the end of February. He turned up at a local health centre for a routine appointment and, when he said he had been to Italy, "panic broke out".
His father was taken to North Manchester General Hospital and the rest of the family were told to self-isolate - with Public Health England sending daily texts asking if they are showing symptoms.
"Since we cannot go outside we regularly called the ward where he was ill," the man's son told BBC Bengali. "And on a daily basis and we asked them how he was. They did not allow me to speak to him directly.
"The first couple of days he was fairly stable but after that they were saying his blood was not oxygenated enough. Also his heartbeat was not stable either."
The son said they received a phone call from the hospital saying his father - who had underlying conditions including arthritis, heart problems, and cholesterol - had died.
"Obviously I could not believe it because two months ago this thing didn't even exist and today it took away my father.
"It took me quite a long time to process the whole thing that I'm not going to be able to see him anymore."
British Airways has cancelled all of its flights to and from Italy until 4 April, and has asked staff to take voluntary unpaid leave.
Ryanair will cancel all its flights to and from Italy from Saturday until 8 April, while Easyjet cancelled the majority of its flights to and from the country and Jet2 cancelled its Italian routes until 26 April.
BA said customers due to fly to or from Italy before 4 April can rebook to a later date until the end of May, move their destination to Geneva or Zurich, or receive a full refund.
A Foreign Office spokesman said: "The advice is that anyone who arrives from Italy subsequent to the Italian government decision should now self-isolate for 14 days."
Downing Street said Italians arriving in the UK were being given the same advice as Britons to self-isolate and that the government had facilities available to accommodate them.
Meanwhile airline Norwegian, which operates from several UK airports, said it was cutting 3,000 flights and reducing staff numbers after a fall in demand it attributed to coronavirus.
The NHS has unveiled a range of measures as part of its response to try to stop fake news being spread about coronavirus on the internet.
Searches for "coronavirus" on Google, Facebook and YouTube will now promote information from the National Health Service or the World Health Organization.
The NHS said it had worked with Twitter to take down an account claiming to be a hospital and spreading false information, while it is also speaking out against homeopaths promoting false treatments online.
Health Secretary Matt Hancock said the actions meant the public could access accurate health information "which is more crucial than ever as we continue our response to coronavirus".
The UK is currently in the first phase - "containment" - of the government's four-part plan.
Asked about statutory sick pay for workers who are not currently eligible, Health Secretary Matt Hancock told MPs that "whatever the status of people" who are employed, the government will "ensure that they will get the support so they're not penalised for doing the right thing".
On Monday, health officials said people who showed "even minor" signs of respiratory tract infections or a fever would - within the next 14 days - be told to self-isolate for a week in an effort to tackle the outbreak.
The UK government has also announced it is to extend shop delivery hours to ensure that supermarkets have basic items, amid stockpiling concerns.
The environment department, Defra, said by allowing night-time deliveries - currently restricted to avoid disturbing locals - stock would be able to move more quickly from warehouses to shelves.
Meanwhile, US authorities are expected to fly home Britons who were on board the virus-hit Grand Princess cruise ship later, according to the Foreign Office.
There were 142 British people on the ship, which spent five days stranded off the coast of California.
However, one of the Britons on board, Jackie Bissell, told BBC Radio 4's Today programme she had yet to hear from the ship's captain about her departure.
"They haven't said anything about when we can go," she said. "It's very unnerving to be left out here when we don't know what's going to happen."
Elsewhere, crowds exceeding 60,000 are expected on all four days of horse racing's Cheltenham Festival, which starts on Tuesday afternoon.
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