Boris Johnson is outlining the next steps in the UK's plan to fight coronavirus at the first of a series of daily news conferences.
The briefing was expected to have details about steps the government may take to protect elderly and vulnerable people.
The over-70s have been told they are allowed to go out for walks when their period of staying at home begins.
The first person in Wales to die with Covid-19 brings the UK total to 36.
Most of those who have died in the UK have been people over the age of 60 with underlying health conditions.
More than 44,000 people have been tested in the UK. People self-isolating with mild symptoms are no longer being tested - the government said tests are primarily being given to hospital patients with respiratory problems, and to people in residential or care facilities experiencing outbreaks.
But on Monday the head of the World Health Organization, Tedros Adhanom Ghebreyesus, said not enough tests were being carried out.
"We have a simple message for all countries: test, test, test," he said - adding that the WHO has sent out almost 1.5 million tests to 120 countries.
Daily news conferences will be led by the prime minister or senior ministers, alongside Prof Chris Whitty, the government's chief medical adviser, and chief scientific adviser Sir Patrick Vallance.
It follows criticism of No 10 for an apparent lack of transparency over its plans to stem the spread of the virus, which causes the disease Covid-19.
Downing Street said the government was committed to keeping the public informed and would be led by science.
Meanwhile, Transport Secretary Grant Shapps told BBC Radio 4's Today programme that over-70s who will soon be asked to stay at home for an extended period would still be able to go for a walk outside.
"It's about being sensible but not mixing in crowds," he said.
And the BBC has said it will delay changes to the TV licence for the over-75s until August. Director General Tony Hall said it was important the corporation served the public "at this difficult time".
Monday's meeting of the government's emergency Cobra committee, chaired by Mr Johnson, included discussions on how to protect the elderly and vulnerable and whether to ban mass gatherings.
Health Secretary Matt Hancock said details of emergency legislation giving the government more powers to deal with the virus will be revealed on Tuesday.
Hotels could be converted to makeshift hospitals and private hospitals could be called on to boost NHS bed numbers.
The government has asked any firms which may be able to help to produce ventilator machines for use in hospitals to get in touch.
Any businesses who can help with the Prime Minister's call for ventilator production please contact @businessgov helpline on 0300 456 3565 or email firstname.lastname@example.org— Alok Sharma (@AlokSharma_RDG) March 16, 2020
Huge thanks to all those companies that have already responded. pic.twitter.com/tcGRcwFIcl
Most schools across the UK remained open on Monday, despite blanket closures in countries such as Spain, France and Ireland.
Some decided to close, however, and Education Secretary Gavin Williamson is due to meet head teachers to discuss their concerns.
Some universities have halted classes and moved all their lectures online while the National Education Union has said it is "unacceptable" for Ofsted inspections to go ahead during the pandemic.
From Tuesday, face-to-face assessments for sickness and disability welfare payments will be suspended for three months.
The suspension will apply to claimants of personal independence payments, employment and support allowance, some on Universal Credit and people on industrial injuries schemes.
The fallout from the pandemic has begun to hit industry. Key developments include:
- Easyjet, British Airways, Virgin Atlantic and Ryanair announced sweeping flight cancellations and warned hundreds of planes would be grounded
- Train companies warned passenger numbers had fallen
- P&O and Cunard said their cruise liners would suspend sailing until 11 April
- The Luton car manufacturing site for Vauxhall will be closed from 19 to 27 March. Vauxhall cited supply disruptions and decline in the automobile markets.
Mr Shapps told BBC Breakfast that good companies "shouldn't be put out of business" due to a downturn caused by the virus.
He will meet airline leaders and discuss potential financial support for businesses with Chancellor Rishi Sunak.
A Public Health England (PHE) briefing, reported by the Guardian, warned the epidemic could last until spring 2021 and put 7.9 million people in hospital.
Downing Street said the PHE briefing outlined a reasonable worst-case scenario.
In other key updates:
- Mr Johnson is due to speak with leaders of the G7 nations in a phone call, asking them to back the World Health Organization response and provide funding and expertise to develop a vaccine
- Defence Secretary Ben Wallace has criticised media reports that the armed forces could be asked to guard supermarkets. He said no such measures were planned
- Britons stuck abroad due to travel restrictions have been advised to contact their airline, as well as the Foreign Office by calling +44 (0)207 008 1500, so that the government knows they are trying to get home
- The Foreign Office is in talks about repatriating 667 British passengers stuck on a virus-hit cruise ship. The Braemar ship anchored in the Bahamas during the weekend
- Labour MP Kate Osborne said she had been diagnosed with coronavirus and was now self-isolating
- A prison officer working at High Down Prison in Surrey has tested positive for the virus, the Ministry of Justice has said. Four prisoners who were in close contact with him have been put in isolation as a precaution
- Global stock markets have sunk despite central banks around the world announcing a co-ordinated effort to ease the effects of the virus. London's FTSE 100 index has fallen more than 8%
- Nationwide Building Society will open some branches an hour early from Wednesday onwards, to give extra support to elderly and vulnerable people
- The BBC said filming for popular dramas Peaky Blinders and Line of Duty has been suspended
- The Old Vic became the first well-known West End theatre to cancel performances because of the virus
- Other arts events to be cancelled include Sir Elton John's upcoming tour dates in the US and Canada, and the British Film Institute's LGBT film festival
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