Sadiq Khan, Mayor of London, declared a “major incident” on Saturday after discussions with NHS London, local councils and other emergency and essential services on the impact of the virus on their workers.

Desperate business leaders have also called for a cut in the period of isolation, claiming the current policy is “lockdown by stealth”.

It is understood the Cabinet’s Covid O (Operational) committee met on Sunday to consider what measures could be introduced to help tackle the impact on supply chains.

It is likely that a reduction in the days in isolation will be allied to a requirement for people to have a negative lateral flow test before they can return to work.

The Tony Blair Institute said there needed to be a review of the rules for self isolation. “With the high number of cases expected in the coming weeks, it is vital only those infectious with the virus are at home,” it said in a report entitled “Staying Ahead of the Covid Curve.”. 

“We suggest careful investigation is undertaken on whether those positive with Covid could take daily lateral-flow tests during their ten-day isolation period and leave isolation when they have had two negative tests. This could allow staff to be back at work safely as soon as possible.”

The Institute also set out two options for NHS staff forced to isolate through Covid contacts after warnings by the British Medical Association (BMA) warning that 50,000 NHS staff could be off sick by Christmas Day.

It said NHS guidelines should be brought in line with those for the rest of the population, where they can leave their home as long as they test, or the introduction of rapid turnaround PCR test so they could get their results within an hour rather than days.

“These rules must be addressed and changed urgently,” said the institute.