Queen Elizabeth II on Sunday thanked healthcare workers on the frontline of the fight against the coronavirus outbreak, promising that a united effort would help defeat the disease.

In a rare special televised address, the 93-year-old monarch drew on her experience in World War II, offering a message of hope to people forced to separate from family and friends.

The broadcast to Britain and Commonwealth nations came as billions of people across the world are forced to stay at home to stop close-contact transmission of the virus.

The monarch and her 98-year-old husband Prince Philip have been at Windsor Castle, west of London, as a precaution since March 19, as the death toll and number of positive tests increased.

Britain currently has 47,806 confirmed hospital cases and 4,934 deaths. Her own son, heir to the throne Prince Charles, and Prime Minister Boris Johnson have both contracted the virus.

The queen warned the situation could persist but said the outbreak would be defeated through a collective effort in a "common endeavour", including through scientific cooperation.

"We will succeed -- and that success will belong to every one of us," she said.

The message -- only her fourth in a time of crisis in her 68-year reign -- was recorded at Windsor, with a single camera operator wearing protective clothing as a precaution.

She personally thanked frontline staff in Britain's state-run National Health Service (NHS), care workers and other key workers for "selflessly" carrying out essential roles.

She also paid tribute to everyone forced to stay at home to reduce the burden on the NHS, and to protect the elderly and vulnerable most at risk from the disease.

The broadcast featured footage of doctors and nurses, workers making deliveries, and military personnel helping to construct a new 4,000-bed field hospital in London.

Members of the public were also seen clapping in appreciation from their homes for frontline staff.

The queen said people in Britain and around the world could feel proud of their community response to the outbreak.

"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.

The queen drew on her experience during World War II, and recalled her first broadcast in 1940 with her sister princess Margaret, addressed to children evacuated from their families.

The sisters were sent to Windsor for safety as London was bombed.

She referenced British wartime singer Vera Lynn, whose song "We'll Meet Again" became an anthem for service personnel fighting abroad, far from their loved ones.

"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."