Severe complications of chickenpox in hospitalised children in the UK and Ireland

Abstract

Aims: To estimate the annual incidence of hospitalisations due to severe complications of varicella, describe the complications and estimate annual mortality.

Methods: Active surveillance throughout the UK and Republic of Ireland for 13 months, by paediatricians notifying cases to the British Paediatric Surveillance Unit and completing a questionnaire. The case definition was any child aged <16 years hospitalised with complicated varicella, as defined by a list of conditions, or admitted to ICU/HDU with varicella.

Results: 188 cases were notified for the surveillance period, of which 112 (0.82/100,000 children/year) met the case definition and were not duplicates. Confirmed cases had a median age of 3 years (range 0-14). The complications were: bacteraemia/septic shock (n=30), pneumonia (n=30), encephalitis (n=26), ataxia (n=25), toxic shock syndrome/toxin-mediated disease (n=14), necrotising fasciitis (n=7), purpura fulminans/disseminated coagulopathy (n=5), fulminant varicella (n=5), neonatal varicella (n=3). Fifty-seven cases (51%) had additional bacterial or viral infections. There were six deaths, due, or possibly due to varicella, including one intrauterine death. Four of the other five deaths (ages 2-14 years) had a pre-existing medical condition. Sequelae on discharge were positively reported for 41 cases (40%), most frequently ataxia or skin scarring. The median length of hospital stay was 7 days (range 1-68).

Conclusions: This study provides a minimum estimate of severe complications and death that occur as a result of varicella in children in the UK and Ireland. The majority of complications, part from deaths, occur in otherwise healthy children and thus would be preventable only through a universal childhood immunisation programme.