Dr Chan Tsz-tai works in the accident and emergency department at Hong Kong’s Queen Mary Hospital. He is among the frontline medical workers who regularly see patients that have suspected Covid-19 infections. Since a test for the coronavirus that causes Covid-19 is the only way to know for sure who is infected, the doctor and his colleagues have no idea whether their A&E patients also have the virus. The uncertainty only adds to the anxiety of their high-stress environment, where Chain says…