Recommending that all U.S. preschoolers get a flu shot cut visits to the emergency department for flu-like illness by more than a third, U.S. and Canadian researchers said on Monday in a study that showed the direct impact of vaccination policy changes on flu transmission. The researchers used real-time data from hospital emergency departments in Boston and Montreal to study the impact of a 2006 change in the United States to recommend flu vaccinations among children aged 2 to 4.
