Why all these changes announced today?
A fresh analysis published by the UK Health Security Agency suggests the Omicron variant will be responsible for at least 50% of Covid cases within two to four weeks.
The prediction is based on the number of cases judged to be suspected Omicron from testing data.
That shows around 2% of daily cases are being caused by the new variant. If that is correct it would mean there are about 1,000 Omicron cases every 24 hours.
What is more, the cases are thought to be doubling every two or three days.
What is not yet known is whether Omicron will completely replace Delta, the variant that is currently dominant.