Mr Johnson has said that anybody who lives with someone with a fever or persistent cough should self-isolate in their homes for 14 days.
He also stated that by the end of the week people with the most serious conditions should self-isolate for at least 12 weeks.
The government has urged people to avoid "non-essential contact" with others from today.
He said: "I know we are asking a lot of everyone.”
Mr Johnson also added that it "may be necessary" to think about school closures, but only "at the right stage" of the outbreak.
Key points:
· Anyone who lives with someone who has a cough or a temperature should stay at home for 14 days
· People should start working from home where they possibly can
· Avoid pubs, clubs, theatres and other such social venues
· Only use the NHS when we really need to
· From tomorrow government will no longer be "supporting" mass gatherings using emergency workers
