| Clinical description | Frequency | Rate (100 000/year)(95% CI) | Median age(IQR), years | Median length of stay(IQR), days |
| Pneumonia (abnormal x ray) | 30 | 0.22 (0.15 to 0.31) | 3.0 (1.0–5.0) | 8.0 (5.0–14.75) |
| Bacteraemia/septic shock | 30 | 0.22 (0.15 to 0.31) | 1.5 (1.0–3.0) | 9.0 (5.0–14.0) |
| Encephalitis | 26 | 0.19 (0.12 to 0.28) | 4.0 (2.0–5.25) | 7.5 (2.75–13.25) |
| Ataxia | 25 | 0.18 (0.12 to 0.27) | 3.0 (2.0–5.0) | 6.0 (1.5–9.0) |
| Toxic shock syndrome/toxin-mediated disease | 14 | 0.10 (0.06 to 0.17) | 3.0 (2.0–4.0) | 6.5 (5.75–10.00) |
| Necrotising fasciitis | 7 | 0.05 (0.02 to 0.11) | 1.0 (1.0–4.0) | 9.5 (6.75–15.25) |
| Purpura fulminans/disseminated coagulopathy | 5 | 0.04 (0.02 to 0.09) | 4.0 (2.0–7.0) | 9.0 (1.0–23.75) |
| Fulminant varicella | 5 | 0.04 (0.02 to 0.09) | 5.0 (4.0–8.5) | 8.0 (2.5–20.0) |
| Neonatal varicella (perinatal infection) | 3 | 0.02 (0.007 to 0.07) or | 0 (0–0) | 2.0 (2.0–4.0) |
| 0.37* (0.12 to 1.13) | ||||
| Reye’s syndrome | 0 | 0 | NA | NA |
| Admitted to ICU/HDU | 29 | 0.21 (0.15 to 0.31) | 2.0 (1.0–4.0) | 12 (6.0–26.0) |
| Death | 6 | 0.04 (0.02 to 0.10) | 4.5 (1.5–11.0) | 2.0 (1.0–2.5) |
*The figures for neonatal varicella are additionally calculated using live births in 2003 as the denominator (n = 757 109).
The denominator for calculation of population rates is the combined estimated mid-year 2003 population estimate for those aged <16 years in England, Wales, Scotland, Northern Ireland and Ireland (n = 12 605 861).