Boris Johnson is to write to every UK household to urge people to stay at home.
The Prime Minister is currently self-isolating at 10 Downing Street after testing positive for coronavirus.
The letter will be sent to 30 million households across the UK next week.
The Tory leader will write: "We know things will get worse before they get better.
"But we are making the right preparations, and the more we all follow the rules, the fewer lives will be lost and the sooner life can return to normal."
The UK has reported 17,089 confirmed cases of coronavirus and 1,019 deaths. The peak of the epidemic in the country is expected to come in a few weeks.
In his letter, Johnson will also thank all those working for the NHS.
Johnson will say: "It has been truly inspirational to see our doctors, nurses and other carers rise magnificently to the needs of the hour.
"Thousands of retired doctors and nurses are returning to the NHS - and hundreds of thousands of citizens are volunteering to help the most vulnerable.
"That is why, at this moment of national emergency, I urge you, please, to stay at home, protect the NHS and save lives."
The letter will come with a leaflet containing the UK government's advice on hand washing, rules on leaving the house, guidance for those self-isolating with symptoms or shielding vulnerable people, and explanations of symptoms.
The letter and leaflet are part of the government's public information campaign on coronavirus, and are expected to cost £5.8million to print and distribute.
