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'.
It comes amid an escalating row about how the epidemic will unfold in the coming months and whether compulsory face masks, working from home and vaccine passports are necessary (shown left on Boris' winter plan). Sajid Javid, the Health Secretary, has promised a 'normal Christmas' this year
There were also 38 coronavirus deaths registered yesterday, down around 16 per cent on the toll last Monday. UK-wide hospital data isn't due until tomorrow.
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.
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