The Impact of Leadership on National Success

European leaders will address the thorny question of vaccine-export controls today. We look at the row with Britain and what it means for the broader relationship with the EU. Our correspondent visits Congo-Brazzaville as the president of nearly 37 years triumphs again—at a continuing cost to his people. And research suggests that Europe’s most inbred rulers were the least adept.For full access to print, digital and audio editions of The Economist, subscribe here www.economist.com/intelligenceoffer