It is five years since the world economy suffered a devastating shock caused by a virus from China. You may think the analogy strange, but we are marking the fifth anniversary of the Covid-19 pandemic with a very similar shock to the world economy, which is manifesting itself in very similar ways.

Numbers of passengers flying to the US from abroad have plunged. Ships full of goods bound for America have been halted. All over the US, companies will soon start to raise prices and shed employees. But the cause of this new shock is not a coronavirus from Wuhan, but a mind virus from Palm Beach, Florida. The mind virus is President Trump’s belief that, by raising the average US tariff rate by a