Coronavirus is "running riot" across all age groups, a scientist advising the Government has warned, as Boris Johnson considers imposing stringent new national lockdown restrictions next week.

The Prime Minister is expected to announce the measures for England – which could see everywhere except essential shops and education settings closed for a month.

A press conference was believed to be scheduled for Monday - but the PA news agency reports that the Prime Minister will host one today (Saturday) at 5pm.

He is expected to be joined by Professor Chris Whitty and Sir Patrick Vallance in Downing Street following a meeting of his Cabinet earlier in the afternoon.

Mr Johnson has so far resisted pressure to introduce nationwide restrictions, opting instead for a localised tier system, but he is facing fresh calls for action after new data showed the extent of cases across England.

The Office for National Statistics estimated that 568,100 people in households were infected with coronavirus in the week ending October 23, and Government scientific advisers believe it is now too late for a two-week national circuit-breaker to have enough of an effect.

Watford Observer:

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In Hertfordshire, the director of public health, warned residents this week it is "only a matter of time" before stricter lockdown measures are introduced for the county, after a "significant" spread of the disease affecting all age groups, including those aged over 60.

Weekly infection rates are over 100 cases per 100,000 people in all but two of Hertfordshire's ten districts, including Watford, Hertsmere, and Three Rivers.

But instead of moving up to Tier 2, Hertfordshire could be forced into even stricter measures, along with the rest of the country.

Read more: Coronavirus hospital admissions in Hertfordshire double in a month - and the latest on deaths, cases, and ages of those affected

Following reports of a looming national lockdown, Professor Calum Semple, a member of the Scientific Advisory Group for Emergencies (Sage), speaking in a personal capacity, told BBC Radio 4’s Today programme: "For the naysayers that don’t believe in a second wave, there is a second wave.

"And, unlike the first wave, where we had a national lockdown which protected huge swathes of society, this outbreak is now running riot across all age groups."

Professor Jeremy Farrar, an infectious diseases expert and Sage member, said on Friday evening that to bring coronavirus under control "we have to act now".

He tweeted: "The best time to act was a month ago but these are very tough decisions which we would all like to avoid.

"The second-best time is now."

"The sooner we get on top of the disease, reduce transmission, the sooner we can get our society back to normal and the economy back on track."

Watford Observer:

Fellow Sage scientist Professor John Edmunds said the only way to have a "relatively safe" Christmas is to take "stringent" action now to bring the incidence of the virus "right down".

He said the current strategy of local lockdowns "guarantees high incidence across the country over the winter", and that, while restrictions do not have to be national, there is a danger that, even in the South West where cases are lower, hospitals will be under pressure within weeks.

His comments came after a senior Government scientific adviser said it is "definitely too late to think that the two-week circuit-breaker on it own will sort this out".

They said the R needs to be brought below one in many places to “get it down to levels that don’t run the risk of breaching health service capacity”, while in other regions the growth needs to flatten for that to happen.

The "longer you leave it”, they warned, “the more difficult it is to turn this around".

Watford Observer:

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Locking down the country again could have "devastating" effects on the nation's economy.

A national lockdown would be "absolutely devastating" for the hospitality industry and "resilience is at rock bottom", businesses leaders have said.

UK Hospitality chief executive Kate Nicholls, Federation of Small Businesses (FSB) national chairman Mike Cherry and British Chambers of Commerce (BCC) director-general Adam Marshall all said that firms will need urgent help to survive.

Ms Nicholls told BBC Breakfast: "People have borrowed up to the hilt and spent money in order to get Covid-secure.

"There is no spare capacity in the tank to be able to fund a lockdown, even for three to four weeks."

Meanwhile, a Whitehall leak inquiry has been launched after details of the Government’s proposals to introduce tougher coronavirus restrictions next week were reported by national newspapers.

The PA news agency understands that Downing Street has now launched an investigation to find the source of the story, amid reports that the Government had wanted to keep the plan quiet until Monday.