BBC News
Published as a result of recent exponential rises in coronavirus cases across parts of England.
London and large parts of Essex and Hertfordshire will move into tier three from Wednesday.
Officials are due to meet on the same day to review the tiers in other parts of the country based on data from last week.
What can the figures tell us about the current situation?
Why were areas moved into tier three early?
When deciding on the initial tiers on 26 November, the government looked closely at the number of cases per 100,000 people - also called the infection rate - across broader county and city regions.