Schools in England are to shut from Friday until further notice, the education secretary has said.
Gavin Williamson said schools would close except for the children of keyworkers such as NHS staff and vulnerable children.
It comes after Scotland and Wales said schools would close from the same day in response to the coronavirus pandemic.
UK deaths reached 104 as the NHS said a further 32 people had died in England.
The government says it plans to more than double the number of tests being carried out in England to 25,000 a day.
Confirmed cases in the UK rose to 2,626 on Wednesday, from 1,950 on Tuesday. There have been 56,221 tests carried out in the UK for Covid-19, of which 53,595 were confirmed negative.
Meanwhile, the government is bringing forward emergency legislation to protect private renters from eviction after being urged to do more for them.