PORTLAND – Maine’s largest city has decided to dispense its sparse supply of flu vaccine by lottery.

Portland ordered 3,000 shots, but because of a nationwide vaccine shortage has only 290. Officials said Wednesday that a lottery is the only fair way to determine who receives the shots.

Portland residents who are 65 or older, pregnant or 19 to 64 with a chronic illness are eligible to sign up for the lottery to be held Oct. 28-29.