Wuhan and US scientists were planning to release enhanced airborne coronavirus particles into Chinese bat populations to inoculate them against diseases that could jump to humans, leaked grant proposals dating from 2018 show. Just 18 months before the first Covid-19 cases appeared, researchers had submitted plans to release skin-penetrating nanoparticles and aerosols containing "novel chimeric spike proteins" of bat coronaviruses into cave bats in Yunnan, China. They also planned to create chimeric viruses, genetically enhanced to infect humans more easily, and requested $14million from the Defense Advanced Research Projects Agency (Darpa) to fund the work. Papers, confirmed as genuine by a former member of the Trump administration, show they were hoping to introduce "human-specific cleavage sites" to bat coronaviruses which would make it easier for the virus to enter human cells. When Covid-19 was first genetically sequenced, scientists were puzzled about how the virus had evolved such a human-specific adaptation at the cleavage site on the spike protein, which is the reason it is so infectious. The documents were released by Drastic, the web-based investigations team set up by scientists from across the world to look into the origins of Covid-19. In a statement, Drastic said: "Given that we find in this proposal a discussion of the planned introduction of human-specific cleavage sites, a review by the wider scientific community of the plausibility of artificial insertion is warranted."