| 2001–2002 study | 2009–2011 study | |||||
| <5 years | 5–16 years | n/N (%) | <5 years | 5–16 years | n/N (%) | |
| Bacterial | ||||||
| Streptococcus pneumoniae | 28 | 7 | 35/238 (14.7) | 14 | 10 | 24/138 (17.4) |
| Mycoplasma pneumoniae | 9 | 13 | 22/176 (12.5) | 2 | 6 | 8/81 (9.9) |
| Group A Streptococcus | 5 | 9 | 14/202 (7.0) | 6 | 8 | 14/133 (10.5) |
| Staphylococcus aureus | 3 | 2 | 5/189 (2.6) | 1 | 2 | 3/130 (2.3) |
| Haemophilus influenzae | 0 | 2 | 2/189 (1.0) | 3 | 0 | 3/130 (2.3) |
| Bordetella pertussis | 1 | 0 | 1/189 (0.5) | 0 | 0 | 0/121 |
| Moraxella catarrhalis | 1 | 0 | 1/189 (0.5) | 2 | 1 | 3/130 (2.3) |
| Streptococcus intermedius | 1 | 0 | 1/189 (0.5) | 0 | 1 | 1/130 (0.8) |
| α-haemolytic Streptococcus | 1 | 0 | 1/189 (0.5) | 0 | 0 | 0/130 |
| Klebsiella pneumoniae | 0 | 0 | 0/189 | 1 | 0 | 1/130 (0.8) |
| Viral | ||||||
| RSV (not typed) | 29 | 3 | 32/213 (15.0) | 0 | 0 | 0 |
| RSV type A | 0 | 0 | 0 | 19 | 0 | 19/147 (13.0) |
| RSV type B | 0 | 0 | 0 | 11 | 1 | 12/147 (8.2) |
| Influenza A and B viruses | 9 | 4 | 13/213 (6.0) | 7 | 4 | 11/149 (7.4) |
| Adenovirus | 11 | 2 | 13/213 (6.0) | 10 | 0 | 10/145 (6.9) |
| Parainfluenza 1–4 | 5 | 0 | 5/158 (3.2) | 5 | 1 | 6/141 (4.3) |
| Human metapneumovirus | 0 | 0 | 0/48 | 1 | 0 | 1/141 (0.7) |
| Epstein–Barr virus | 0 | 1 | 1/1 (100) | Not tested | Not tested | |
| Varicella zoster virus | 0 | 1 | 1/1 (100) | Not tested | Not tested | |
| Rhinovirus | Not tested | Not tested | 10 | 2 | 12/141 (8.5) | |
| Pandemic influenza A H1N1 | Not tested | Not tested | 4 | 3 | 7/141 (5.0) | |
| Bocavirus | Not tested | Not tested | 2 | 2 | 4/121 (3.3) | |
| Coronavirus (type OC43) | Not tested | Not tested | 2 | 1 | 3/121 (2.5) | |
| Total | 103 | 44 | 147 | 100 | 42 | 142 |
Data are presented as n, unless otherwise stated. N represents the total number of performed tests with positive results classified as definite/probable infections. RSV: respiratory syncytial virus.