UNITED AIRLINES SAYS 97 PERCENT OF US EMPLOYEES FULLY VACCINATED; EMPLOYEES WHO REFUSE TO GET VACCINATED OR DO NOT RECEIVE AN EXEMPTION WILL START TO BE FIRED ON SEPT. 28; THOSE WHO RECEIVE AN EXEMPTION WILL BE PUT ON AN UNPAID TEMPORARY LEAVE STARTING SEPT. 28 UNTIL THE COMPANY DEEMS IT IS SAFE FOR THEM TO RETURN TO WORK