The global economic recovery from Covid-19 may be underway, but external trade flows have seen an uneven and, in some sectors, a fragile path to health. Macroeconomic data suggests that over the first four months of 2021, aggregate global trade flows have been running at the levels that exceed the same period of 2020 and are close to the pre-pandemic 2019 levels. But all is not well, yet. At least not across the board. In a year through April 2020, US merchandise trade rose 42 per cent year on year, and is now up 8.9 per cent in April 2019.…