Boris Johnson is warned that Covid ‘Plan B’ would cost economy £18billion

Switching to ‘Plan B’ to curb coronavirus could cost the economy up to £18billion this winter, according to internal government documents.

An estimate for the damage from reverting to working from home and face masks has been produced by the Treasury and Cabinet Office.

The document, leaked to Playbook, cites an ‘assumption’ that the alternative approach – which would also include Covid passports – would stay in place for five months.

Although the scale of the hit is relatively small compared to the £2trillion annual output of UK plc, it underlines why ministers have been unwilling to have a knee-jerk reaction to increasing infection levels.

In a glimmer of hope for the government, there are signs that the surge in cases might be easing.    

The government reported 36,657 new infections yesterday, down a quarter on the figure last week and the second day in a row there has been a week-on-week drop. Cases had risen for 18 days prior to Sunday.

Many experts suggest that the October half-term — which for many schools is this week — will drag infection rates down and act as a miniature ‘firebreaker’.  

There were also 38 coronavirus deaths registered yesterday, down around 16 per cent on the toll last Monday.  

A technical issue meant the promising statistics do not include data from Wales, which is recording on average 3,200 daily cases and nine deaths per day. The trajectory of the epidemic is likely to remain unchanged, even with the inclusion of Wales’ infection numbers.

Downing Street today insisted it has ‘no plans’ to deviate from the current Covid strategy, but urged patience on the dip in numbers.

‘It’s always encouraging when you see reductions like that and including, I believe, a levelling off of admissions,’ the PM’s spokesman said.

‘But it’s too early to draw full conclusions from the case rates and we would continue to urge the public to abide by the guidance as set out and those eligible to get booster doses.’ 

There is an escalating row about how Britain’s epidemic will unfold in the coming months and whether compulsory face masks, working from home and vaccine passports are necessary. 

Independent scientists told MailOnline they expect that a combination of the booster vaccine rollout and rising natural immunity in children will lead to a ‘substantial and rapid’ fall in cases, hospitalisations and deaths in weeks.

The topic has also divided No10’s own scientific advisory panel SAGE, with several key members publicly lobbying for more restrictions to safeguard the NHS from being overwhelmed in the coming months.

But many of the scenarios forecasted by the group’s modelling teams have daily cases plunging over the coming weeks to as low as 5,000, even if the virus is allowed to spread unchecked.  The unusually optimistic modelling has given ministers the confidence to reject growing calls for them to revert to Plan B. 

Professor Paul Hunter, an infectious diseases expert at the University of East Anglia, threw his support behind the modelling, telling MailOnline he expects a ‘substantial and rapid fall’ in the epidemic in the coming weeks. 

He said the booster vaccines will top up half of the population’s immunity, adding: ‘The boosters are working much better than we first thought they would.’

And children, who are responsible for the recent surge, will have acquired significant natural and jab-induced protection, according to Cambridge University epidemiologist Dr Raghib Ali.  

However, neither Professor Hunter or Dr Ali believe cases will plunge to as low as 5,000 per day, partly because of the emergence of the new even more transmissible strain of Delta. 

Other scientists have warned it is impossible to accurately predict how the outbreak will unfold and that Plan B measures — such as WFH guidance and face masks — should be brought back now to control rising infections just in case. 

Professor Martin McKee, a public health expert based at the London School of Hygiene and Tropical Medicine, said he would be ‘very cautious about making firm Christmas arrangements’ because of the ‘high’ number of cases and emergence of the AY.4.2 variant which appears ‘more transmissible than Delta’. 

Modelling for SAGE from the London School of Hygiene and Tropical Medicine (LSHTM) shows cases could fall to 5,000 per day over Christmas after the virus runs out of steam among younger people who are driving the current high case numbers levels.

Some 5.2million boosters have already been dished out in England, but there has been criticism the rollout is not moving fast enough.

In another optimistic sign, data from Israel show booster jabs significantly reducing cases and hospitalisations. 

A Government spokeswoman said: ‘We knew the coming months would be challenging, which is why we set out our Autumn and Winter plan last month. 

‘Plan B ensures we are ready, should we need to act, to avoid an unsustainable rise in hospitalisations which would put unsustainable pressure on the NHS. 

‘The presumptions put forward do not reflect government policy. The data does not currently show that Plan B is necessary – and there is no planned five month timeline.’