Influenza (the "flu") is one of the most common respiratory viruses associated with respiratory deteriorations in children and adolescents with cystic fibrosis. These deteriorations usually mean antibiotics, hospitalizations, and worsening of pulmonary function tests. A new flu vaccine has been recently approved for use in Canada (Flumist®). What is particular about this flu vaccine is that it is a spray in the nose, which mimics how influenza usually infects us. This particular vaccine protects children and adolescents much better than the regular injectable flu shot.