MIT Technology Review: “In the unprecedented outbreak of a new coronavirus sweeping the world, the germ’s genetic material may ultimately tell the story not just of where it came from, but of how it spread and how efforts to contain it failed.By tracking mutations to the virus as it spreads, scientists are creating a family tree in nearly real time, which they say can help pinpoint how the infection is hopping between countries. When scientists in Brazil confirmed that country’s first case of coronavirus late in February, they were quick to sequence the germ’s genetic code and compare it with over 150 sequences already posted online, many from China. The patient, a 61-year-old from São Paulo, had traveled in Italy’s northern Lombardy region that month, so Italy was likely where he acquired the infection. But the sequence of his virus suggested a more complex story, linking his illness back to a sick passenger from China and an outbreak in Germany. As a virus spreads, it mutates, developing random changes in single genetic letters in its genome. By tracking those changes, scientists can trace its evolution and learn which cases are most closely related. The latest maps already show dozens of branching events.

The data is being tracked on a website called Nextstrain, an open-source effort to “harness the scientific and public health potential of pathogen genome data.” Because scientists are posting data so quickly, this is the first outbreak in which a germ’s evolution and spread have been tracked in so much detail, and almost in real time.