The Trump administration has urged US states to get ready to distribute a potential Covid-19 vaccine by November 1, in the latest sign of the accelerating race to deliver a vaccine by year’s end.“CDC urgently requests your assistance in expediting applications for these distribution facilities,” read an August 27 letter from Robert Redfield, director of the Centres for Disease Control and Prevention.Dallas-based wholesaler McKesson Corp. has a deal with the federal government to set up centers…