having a simple clear runny nose and occasional cough that can be treated at home, to severe difficulty breathing that may require hospitalization. Other symptoms might include a low-grade fever, sore throat, headache, and irritability. Younger children, especially those under 2 or 3 years old, are most at risk for more severe symptoms, such as high fever, wheezing, difficulty breathing, a persistent cough, or apnea.
I hope this helps.