Bronchiolitis Age Range
Bronchiolitis typically affects children from 1 month through 23 months of age, with the highest incidence occurring in the first year of life, particularly peaking between 3 and 6 months of age. 1
Guideline-Defined Age Parameters
The American Academy of Pediatrics (AAP) clinical practice guideline specifically addresses bronchiolitis in children from 1 month through 23 months of age (essentially birth to less than 2 years). 1 This represents the standard age range for which bronchiolitis diagnosis and management protocols apply.
Peak Incidence Patterns
First year of life: Bronchiolitis most commonly affects infants during their first 12 months, with peak incidence between 3 and 6 months of age. 2
Highest admission rates: Infants less than 3 months old have the highest rates of hospital admission for bronchiolitis. 2
RSV infection patterns: Ninety percent of children are infected with respiratory syncytial virus (RSV), the most common cause of bronchiolitis, within the first 2 years of life, with up to 40% experiencing lower respiratory tract infection during their initial infection. 1
Age-Related Diagnostic Considerations
Diagnostic variability increases with age, particularly in the second year of life. 3 In children aged 12 to 23 months, there is significant overlap between bronchiolitis and asthma presentations, with bronchiolitis comprising 98% of encounters in infants under 3 months but decreasing to 56% by 23 months of age (with asthma diagnoses accounting for 44% at that age). 3
Clinical Context by Age
Very young infants (under 3 months) may present with apneic episodes as a prominent feature rather than typical wheezing. 2
Severity tends to be greater in younger children (1-12 months) and decreases with advancing age. 4
The condition is most commonly the first episode of wheezing in affected children under 2 years. 4
Important Caveats
While the guideline age range extends to 23 months, some specialized guidelines for severe bronchiolitis requiring intensive care focus on infants under 12 months of age, recognizing this as the highest-risk population. 5 However, the broader clinical definition and management principles apply through the full 1-23 month age range as defined by the AAP. 1