M&S boss warns store hours may have to be cut with up to one in five supermarket staff forced into Covid isolation in Freedom Day 'pingdemic' chaos Thousands of Britons are currently confined to their homes after being 'pinged' by NHS Track and Trace app Situation almost certain to worsen after Freedom Day, as cases rise and people resume near-normal routines Marks and Spencer boss warns one in five supermarket workers could be in self-isolation by mid-August and the chain may have to reduce store opening hours as a result Others have warned of food shortages as supply chain workers are caught up in the 'pingdemic' chaos