Demographic characteristics
| Category | N (%) | |
| Gender (N=180) | Male | 92 (51%) |
| Female | 88 (49%) | |
| Age (years) | Median, range | 4 (0.01–17) |
| Age category | Infant (0–12 months) | 41 (23%) |
| Toddler (13–24 months) | 27 (15%) | |
| Preschool (3–5 years) | 36 (20%) | |
| School aged (6–12 years) | 54 (30%) | |
| Adolescent (13–19 years) | 22 (12%) | |
| Underlying medical disease (N=52) | Bronchial asthma/chronic airway disease | 20 |
| Immunodeficiency, immunesupression or chemotherapy | 14 | |
| Complex neurologic disease | 7 | |
| Congenital heart disease | 6 | |
| Other disorders | 5 |