People are being urged to work at home if possible, stop unnecessary travel, avoid gatherings whether small or large and reduce social contacts as the government ramps up measures to delay the spread of the virus across the UK. The move means visits to public places such as theatres, pubs and cinemas are effectively off-limits.
Further measures could be implemented within days to protect patients in at-risk groups, the government's chief scientific adviser has said, along with school closures at some stage. People over 70, people in at-risk groups who receive the annual flu vaccination, and - as a precaution - women who are pregnant will soon be asked to minimise social contact for a period of 12 weeks or longer.
The decision to step up the government's approach came as NHS England confirmed a further 19 patients had died after being infected with coronavirus - taking the UK death toll to 53. A total of 1,534 cases have been confirmed UK-wide - nearly one in three of them in London.
Explaining the change in approach, chief scientific adviser Professor Sir Patrick Vallance said measures such as keeping people with symptoms at home could have a 'dramatic effect to reduce the peak and the death rate' from coronavirus infection.
CMO Professor Chris Whitty said whole-household isolation for 14 days was intended to allow time for the infected person and others in the house to contract and recover from the illness without passing on COVID-19 to a wider group.
'If one person gets the symptoms of new persistent cough or fever the whole household stays isolated for 14 days,' he said. 'The reason it is 14 days, is the seven days for the person who has got the infection, the incubation period for others who may catch it and the seven days after that.'
New guidance released following the press conference confirmed that the person who is symptomatic can end their isolation period after seven days. All other household members should remain at home until 14 days after the first person became ill, or seven days after their own symptoms resolve if they become ill.
Professor Whitty said: 'In this country this disease is now accelerating up the curve, although it is still at a low level and will accelerate now really quite rapidly.'
The chances of any individual dying from coronavirus were 'actually very low', he said, with the likely mortality rate looking like it was 'a bit less than 1%'.
He pointed out that although older people were at increased risk, 'being old does not necessarily mean you will get it worse' - pointing to the case of health minister Nadine Dorries, whose mother caught the illness from her and experienced milder symptoms.
NHS testing capacity was being scaled up 'every single week', Professor Whitty told a Downing Street press conference on 16 March.
Responding to calls from doctors' leaders for the immediate rollout of testing for frontline NHS staff to avoid doctors, nurses and other workers with symptoms being forced to self-isolate - potentially unnecessarily - for extended periods, Professor Whitty agreed there was a 'very strong incentive' to build NHS testing capacity to the point where this was possible.
'The next level out once we have the capacity to do this - which we are going for very fast - is that healthcare and other critical workers can be tested early in their illness. If they have the symptoms but not coronavirus they will be able to go back to work - if they have got it you know they are not going to get it again, so a positive or a negative are useful for the service.'