Continuity mistake: Chandler is reviewing the President's paperwork and finds the manifests which brought his wife and daughters from Washington (document dated 07-05-13) and his son from Detroit (document dated 08-02-13). He then checks the computer for casualty figures in Michigan where the son was originally from (dated 8/4/14-onwards). So the plague hit in early August 2014, but the documents show the family leaving their home a full year earlier. This is not a plot issue (no, they did not fly out a year prior to the plague), but rather a prop-maker error.
xx:xx:xxDavid R Turner