BARCELONA — On Friday, hours after the World Health Organization announced the appearance of a new, heavily mutated coronavirus variant in southern Africa, European Commission President Ursula von der Leyen urged the 27 countries of the European Union to “activate the emergency brake” and block flights from South Africa and seven nearby countries where the variant of concern, soon named Omicron, had been detected.
By then, however, Omicron had already arrived on the European continent, appearing at least as early as Nov. 19 in the Netherlands. And in the past few days it’s been showing up everywhere from the United Kingdom to the Czech Republic, although most of the 79