The Centers for Disease Control and Prevention (CDC) is recommending all Americans older than six months be vaccinated against the flu. Although last year’s flu season was relatively mild, the CDC warns that Americans should not be complacent about the flu. It recommends that people be vaccinated in October, before the flu season kicks into full gear. During the 2011-12 flu season, 128 million Americans (or 42 percent) received a flu shot.