Flu viruses circulate around the world throughout the year but a flare up in the U.S. is most common in the fall and winter hitting it's worst point between December and February according to the Centers for Disease Control.
根据疾控中心
数据,流感病毒全年都在全世界范围内传播,在美国,秋冬季节
流感爆发最为严重,12月至次年2月是最高峰。