U.S. Making Flu Shots Priority for the Elderly By MICHELLE SPITZER     JOHNSTON, Iowa (AP) -- Health officials are scurrying to secure flu vaccines so the elderly, who are most vulnerable to influenza, have first access to shots after the nation's supply was cut in half.    "We're begging, borrowing and stealing from every source we can come up with," said Paula Frank, a clinical consulting nurse for the Bishop Drumm Retirement Center...