London, Jun 22 (IANS): UK Prime Minister Boris Johnson has warned of a "rough winter" as pressure on the National Health Service (NHS) could intensify due to possible new diseases amidst the Covid-19 pandemic.

"You can never exclude that there will be some new disease, some new horror that we simply haven't budgeted for or accounted for," Johnson said on Monday as he did not rule out the prospect of further lockdowns in the winter.

"Obviously there are big pressures on the NHS, which is all the more reason to reduce the number of Covid cases now, give the NHS the breathing space it needs to get on with dealing with all those other pressures.

"We're certainly going to be putting in the investment to make sure that they can," he added.

The Prime Minister said cases of the Delta variant are still rising and the public have to remain cautious, reports Xinhua news agency.

"It's going up by about 30 per cent a week in cases, hospitalizations are up by roughly the same amount and so, sadly, are ICU (intensive care units) admissions into intensive care.

"We've got to be cautious but we'll be following the data the whole time. But looking at where we are, the efficacy of the vaccine against all variants that we can currently see.

"I think it is looking good for July 19 to be that terminus point," Johnson added.

The Prime Minister has announced a four-week delay to the final step of England's roadmap out of Covid-19 restrictions until July 19, amid a surge in cases of the Delta variant.

Recent data published by Public Health England showed the AstraZeneca vaccine is 92 per cent effective against the Delta variant after two doses, while the Pfizer jab is 96 per cent effective.

Nearly 43 million people have been given the first jab of a coronavirus vaccine while more than 31.3 million people have been fully inoculated with a second dose, according to the latest official figures.

The UK has reported a total of 4,656,535 coronavirus cases and 128,245 deaths.