What age group is most commonly affected by bronchiolitis?

The age group most commonly affected by bronchiolitis is typically infants ranging from newborns to 6 months. Bronchiolitis is primarily caused by viral infections, with respiratory syncytial virus (RSV) being the most common culprit. This condition predominantly affects small airways in the lungs—known as bronchioles—and is particularly prevalent in very young children because their airways are smaller and more susceptible to obstruction and inflammation.

Infants within this age range are also at a developmental stage where their immune systems are still maturing, making them more vulnerable to respiratory infections. The peak incidence of bronchiolitis occurs in infants under 6 months of age, with a significant number of hospitalizations for bronchiolitis occurring in this group. As children grow older, particularly beyond 2 years, they develop stronger immune responses and their airways increase in size, thus reducing the likelihood of severe bronchiolitis. Therefore, the younger infants are the most commonly affected demographic.