Last Year's Flu Shot Imperfect But Effective By Amanda Gardner, HealthDay Reporter    HealthDayNews -- Last year's influenza vaccine was far from a perfect match against the virus that sickened people, but it offered more protection from the illness than experts had previously thought.    In very young children, the shot was found to be 25 percent to 49 percent effective in preventing influenza-like illness, which is a suspected case of flu that wasn't confirmed in a laboratory...