A Chinese military scientist who was reportedly thrown to his death from the roof of a Wuhan institute is at the centre of mounting evidence that the Covid pandemic resulted from a lab leak. Intelligence obtained by members of the US Senate reveals that Zhou Yusen filed a patent for a Covid-19 vaccine on February 24, 2020, barely a month after China put Wuhan into lockdown because of the outbreak. US vaccine developers told investigators that it would have been impossible to have generated the data cited in the patent so swiftly – it would have taken about three months'...