The aetiology of CAP requiring hospitalisation in children across Europe
| Pathogen | Frequency (%) |
| Respiratory syncytial virus | 20–28 |
| Rhinovirus | 15–27 |
| Human metapneumovirus | 10–13 |
| Adenovirus | 4.3–27.0 |
| Mycoplasma pneumoniae | 8.0–8.2 |
| Parainfluenza viruses | 4.7–7.0 |
| Influenza viruses | 6.9–7.0 |
| Streptococcus pneumoniae | 4.0–25.3 |
| Haemophilus influenza e | 32.6 |
| Moraxella catarrhalis | 44.7 |
The main causative organisms for CAP are listed, with frequency expressed as a percentage. Adapted from Bhuiyan et al 12 and Jain et al.13