Concern is growing that the spread of COVID cases and city lockdowns in China will have massive downstream effects for global supply chains that could dwarf previous disruptions since the start of the pandemic.  Last May, the huge Yantian container terminal at the Port of Shenzhen throttled down to 30% of normal productivity for a month to stamp out a handful of positive cases there. Hundreds of thousands of shipments that couldn’t enter the port accumulated in factories and warehouses, and many vessels skipped the port to avoid waiting seven days or more at anchor. It took ...