Omicron is expected to be the dominant variant in London in the next 48 hours, the Secretary of State for Health and Social Care, Sajid Javid, warned in a statement to Parliament Monday.

Omicron represents 20 percent of England's cases and 44 percent of London's cases, Javid said.

"No variant of COVID-19 has spread this fast," Javid said.

Ten people with omicron are in U.K. hospitals.

"Hospitalizations and deaths lag infections by around two weeks," Javid said, "So we can expect those numbers to dramatically increase in the days and weeks that lie ahead."

"In preparation, the UK's four Chief Medical Officers raised the COVID Alert level to 4, its second-highest level, this was done over the weekend. And NHS England has just announced it will return to its highest level of emergency preparedness: Level 4 National Incident," Javid said. "This means the NHS response to Omicron will be a coordinated as a national effort, rather than led by individual trusts."

Javid also urged people to get booster doses, stating that 40 percent of adults in the U.K. have gotten boosters so far.

(With input from agencies)