British Prime Minister Boris Johnson warned on Monday that the country’s health system will remain under strain for weeks amid the current surge in coronavirus infections, but suggested there would be no tightening of measures soon to slow the spread.

The highly transmissible omicron variant has sent Britain’s daily new caseload soaring over Christmas and the New Year, with 157,758 infections reported for England and Scotland on Monday and and 42 deaths in England. Figures for Wales and Northern Ireland were not released.

“I think we’ve got to recognize that the pressure on our NHS, on our hospitals, is going to be considerable in the course the next couple of weeks, and maybe more,” Johnson said during a visit to a vaccination center in Aylesbury, 85 kilometers (53 miles) northwest of London.

Johnson was speaking after The Sunday Times newspaper reported that a group of hospitals in the eastern county of Lincolnshire had declared a “critical incident” due to “extreme and unprecedented” staff shortages. 

Chris Hopson, chief executive of NHS Providers, which represents health trusts that run hospitals around the country, told the BBC: “We’re seeing increasing staff absences, and that’s coming on top of a very significant amount of wider pressure.”