The first people in the UK are in hospital with Omicron infections, Nadhim Zahawi has said.
The new variant of coronavirus now accounts for a third of cases in London, the education secretary said.
With two doses of a vaccine not enough Mr Zahawi encouraged people to get a booster jab – those aged 30 and over are eligible to do so from Monday.
As of Sunday, there have been 3,137 confirmed cases of the Omicron variant in the UK.
Scientists from the London School of Hygiene and Tropical Medicine LSHTM have warned that the UK will face a substantial wave of Omicron infections without further restrictions beyond the Plan B measures announced last week.
These include recommending people work from home if they can, expanding mask-wearing rules and introducing Covid passes for entry to some venues – with parliament to vote on the changes on Tuesday.
People in England with two or more jabs who are close contacts of Covid cases will be told to take daily lateral flow tests for seven days from Tuesday.
It means people in close contact with suspected or confirmed Omicron variant cases no longer need to self-isolate.
Mr Zahawi told BBC One’s Andrew Marr Show the new variant was a big bump in the road on the journey from pandemic to epidemic.
He said a national endeavour was needed on the vaccine roll-out with the country in a race against Omicron.
The current measures in response to the variant were proportionate, the education secretary added.