RSV
Respiratory syncytial virus—RSV—is an infection of the respiratory tract that may seem like a cold or the flu that’s easily spread through coughing and sneezing. Symptoms include fever, nasal congestion, a barking cough, difficulty breathing, and lethargy. “The virus causes the most trouble for very young children in the first year of life,” warns Dr. Cloonan. Call a doctor immediately if children exhibit these symptoms.