Sajid Javid told MPs Omicron cases could exceed 1 million by the end of this month on the current trajectory.
It comes as Boris Johnson announced Plan B will be implemented in England - including Covid passes and work from home measures.
In the House of Commons, the Health Secretary delivered a statement on the Omicron variant.
He said there are 568 confirmed cases of the Omicron variant but the estimated current number is “probably closer to 10,000”.
He said: “Although there are only 568 confirmed Omicron cases in the UK we know that the actual number of infections will be significantly higher.
“The UK health security agency estimates that the number of infections are approximately 20 times higher than the number of confirmed cases, and so the current number of infections is probably closer to 10,000.
“UKHSA also estimate that at the current observed doubling rate of between two and a half and three days, by the end of this month, infections could exceed 1 million.”
The Health Secretary explained Omicron is more transmissible than Delta but he said there was still a lot to learn about the new variant.
He told the Commons: “We’re confident that Omicron is significantly more transmissible than Delta.”
Speaking in the Commons he said: “There is still a lot to learn, but some important data has emerged recently.”
He added: “It is far more transmissible than the Delta variant.”
He said Delta cases had doubled in around seven days but for Omicron “based on the latest data from here and around the world, our latest analysis is that it’s been around, it’s between 2.5 and three days.
“This has made the virus an even more formidable foe.”
