Scientists dispute a suggestion that SARS-CoV-2 was engineered

about 30,000 genetic letters was all it took to start the nightmare of covid-19, the death toll from which is likely to be more than 20m. Exactly how the story began is hotly contested. Some think the infection was a zoonosis—a spillover from wild animals. Its cause, -o-2, resembles a group of coronaviruses found in bats. Others, though, have pointed to the enthusiastic coronavirus engineering going on in laboratories around the world, especially in Wuhan, the Chinese city where the virus was first identified.Recent work has bolstered the case for it being a zoonosis connected with a particular “wet market” in Wuhan selling wild animals. However, uncertainties around this conclusion allow other theories to flourish. On October 20th an un-peer-reviewed “preprint” was published on a server called , claiming to show that -o-2 is the product of genetic engineering.