A Time of Angels — Karen Hesse

OUT OF THE BLUE
When war separates Hannah from her parents in 1918, she moves to her aunt's crowded tenement in Boston's West End. Together, Hannah and Tanta Rose struggle to protect Hannah's two young sisters, but when a deadly influenza epidemic strikes, the family is torn apart. Guided by a vision of a girl with violet eyes, Hannah, who also has come down with the dreaded flu, is driven from Boston to a caring old gentleman in Vermont, where she remains until she is healthy. Hannah is still determined to reunite her family, but does she have the strength?