The leader of the World Health Organization’s investigation into the origins of COVID-19 told a Danish documentary crew that Chinese researchers blocked in-depth study of highly contentious “lab leak” scenarios. The accidental release of a natural virus sample is not implausible, but the possibility is both unsubstantiated and deeply politicized. While on one hand such theories have often been promoted well beyond the strength of any available evidence, Chinese authorities have done their utmost to ensure that any evidence remains unavailable. Ben Embarek led the World Health Organization’s on-the-ground investigation into the virus’ origins. The report was criticized even by…