More than 16 million Britons are now required to stay at home after a lockdown came into force Sunday in London and southeast England and the government scrapped plans to relax rules on socializing at Christmas.

The measures to control the fast-spreading new variant of the virus forbid household mixing in those areas and restrict socializing to just Christmas Day across the rest of England. Residents across the country were told to keep to their local areas, and extra police were being deployed at rail stations to stop people traveling out of London.

“Cases have absolutely rocketed, so we’ve got a long way to go,” Hancock told Sky News. “I think it will be very difficult to keep it under control until the vaccine has rolled out.” People in the new Tier 4 areas “should behave as though they have it,” he said.