The global spread of covid-19 seems to have exploded in recent days, with outbreaks revealed in Iran and Italy and a massive increase in cases in South Korea. Tedros Ghebreyesus, director-general of the World Health Organization, has warned that such cases “show that the window of opportunity we have for containing this virus is narrowing”. In fact, it may already have shut. On 21 February, epidemiologists warned that we are failing to detect two-thirds of infected people traveling globally, “potentially resulting in multiple chains of as-yet undetected human-to-human transmission outside mainland China”. Some of those chains have now been detected, and, ominously, many cases can’t be traced to their source. Iran has reported 28 cases, but this appears to be a large underestimate because two people who […]