The Queen has said the UK "will succeed" in its fight against the coronavirus pandemic, in a rallying message to the nation.
In a rare speech, the monarch thanked people for following government rules to stay at home and praised those "coming together to help others".
She also thanked key workers, saying "every hour" of work "brings us closer to a return to more normal times".
It comes as the number of people to die with the virus in the UK reached 4,934.
'We will meet again'
Speaking from Windsor Castle, the Queen said: "While we have faced challenges before, this one is different."
"This time we join with all nations across the globe in a common endeavour, using the great advances of science and our instinctive compassion to heal. We will succeed - and that success will belong to every one of us.
"We should take comfort that while we may have more still to endure, better days will return: we will be with our friends again; we will be with our families again; we will meet again."
The Queen, 93, also said the "painful sense of separation from their loved ones" that social distancing was causing for people reminded her of the experience child evacuees had during the Second World War.
"Now, as then, we know, deep down, that it is the right thing to do," she said.
An hour after the Queen's broadcast, Downing Street announced that Prime Minister Boris Johnson had been taken to hospital following his coronavirus diagnosis.
Mr Johnson has been self-isolating since he tested positive for the virus on 27 March.
In her address, the Queen said everyone who was following guidance to stay at home was "helping to protect the vulnerable and sparing many families the pain already felt by those who have lost loved ones".
"Together we are tackling this disease, and I want to reassure you that if we remain united and resolute, then we will overcome it," she added.
She also stressed the value of self-discipline and resolve - and said she hopes that, in the future, everyone would "be able to take pride in how they responded to this challenge".
'Ambitious message' to inspire nation
There have been difficult royal speeches and addresses in the past - times when the wrong word or the wrong phrase could have undermined the message or let slip a critical opportunity.
The broadcast after the death of Diana, Princess of Wales in 1997 for example, or the speech the Queen gave on her visit to Ireland in 2011.
The Palace could have played it safe, stressed unity and given thanks. It would have served.
This was a different and much more ambitious broadcast, designed to reassure and to inspire.
But most of all to recast this crisis as a defining moment in a nation which will forever remember its collective effort to save the lives of its vulnerable.
The pre-recorded message, written by the Queen with her private secretary Sir Edward Young, was filmed by a single cameraman wearing protective equipment. All other technical staff were in another room.
It was broadcast on TV, radio and social media channels.
The decision to deliver the address was made "in close consultation with Downing Street", BBC royal correspondent Nicholas Witchell said.
Nightingale Hospital - the first temporary field hospital to open to treat coronavirus patients - shared photos on Twitter of staff listening to the speech, and thanked the monarch for recognising the hard work of frontline NHS staff.
The UK government's Health Secretary Matt Hancock said the Queen's address was "striking and important".
The new Labour leader Sir Keir Starmer said the monarch spoke for the whole country "and our determination to defeat the coronavirus".
The Queen's address came less than a week after her son, the Prince of Wales, came out of self-isolation, following his coronavirus diagnosis.
Prince Charles, 71, spent seven days self-isolating in Scotland after testing positive and displaying mild symptoms.
The Queen's four other special addresses
It is only the fifth time the monarch has given such a speech in her 68-year reign.
While her Christmas Day message is an annual event, only rarely has the Queen made rallying speeches at key moments in the life of the nation:
- A televised speech to celebrate her Diamond Jubilee in June 2012
- A special address to the nation on the eve of her mother's funeral in April 2002
- A live broadcast on the eve of the funeral of Diana, Princess of Wales, in September 1997
- And a statement at the beginning of the land war in Iraq on 24 February 1991
On Sunday Mr Hancock urged the public to follow social distancing rules over a sunny weekend to protect the NHS and slow the spread of the virus.
The Department of Health said on Sunday there had been 621 more coronavirus-related deaths in the UK in the past day.
As of 09:00 BST on Sunday, 47,806 people had tested positive for the virus, the Department of Health said.