Traffic in Magnolia backed up for more than a mile Monday as Medicare patients took advantage of a drive-through flu shot clinic. Officials say 370 participants in the health care plan for the elderly got their shots this morning while sitting in their cars. The shots were given by Magnolia Hospital. The traffic backup began early. The first person in line said he arrived at 3:15 a.m. The hospital started giving shots at 7:50 a.m. and ran out of vaccine at 9:25 a.m., when there was still a long line of cars.