Severe complications of varicella (chickenpox) in hospitalised children
When this study started surveillance, there was little data on complicated varicella cases in the UK. Analysis of routine hospital discharge records, but did not provide data with sufficient detail or accuracy. There was no routine childhood immunisation programme against varicella in the UK or Ireland. Data from the study on severe complications of varicella would have made a valuable contribution to the epidemiological and economic data available. It would also assist in determining the advisability of a universal or selective immunisation. The data would additionally provide a baseline for a vaccination programme for its evaluation.
Lead investigator
Dr J C Cameron
About the study
The varicella-zoster virus causes varicella (chickenpox) and herpes zoster upon subsequent reactivation.
When this study started surveillance, approximately 90% of varicella cases occurred in children aged less than 15 years, with the highest incidence of infection in the one to four year age group. Varicella was generally a mild disease, but immunocompromised individuals and neonates with maternal rash onset temporally close to birth were at greatly increased risk of complications. Nevertheless, severe complications could occur even in previously healthy children, including secondary bacterial infections, central nervous system manifestations and death. There was little data on complicated varicella cases in the UK. Analysis of routine hospital discharge records, but did not provide data with sufficient detail or accuracy.
In the 1970s, a live-attenuated vaccine was developed and was shown to be safe and effective. It was recommended for routine use in all healthy children in several countries, including the United States and Canada. The vaccine had been reported to prevent varicella in 85% of immunised children, with 97% protection against moderately severe and severe disease.
There was no routine childhood immunisation programme against varicella in the UK or Ireland. The vaccine was licensed and recommended for certain seronegative healthcare workers and individuals at particularly high risk of complications, including their seronegative contacts. Decisions around the possible introduction of the varicella vaccine were complex, and it seemed doubtful whether the UK Joint Committee on Vaccination and Immunisation would recommend its administration to all healthy children in the future.
Nevertheless, data on severe complications of varicella would have made a valuable contribution to the epidemiological and economic data available. It would also assist in determining the advisability of a universal or selective immunisation. The data would provide a baseline for a vaccination programme for its evaluation.
Objectives
- To estimate the annual incidence of complicated varicella in hospitalised children <16 years of age.
- To describe the characteristics of these complications and the affected children (e.g. age, underlying medical conditions).
- To estimate the annual financial cost of hospitalisation for severe varicella.
- To estimate the annual mortality from varicella in children.
Duration
November 2002 – November 2003
Published papers
Cameron JC, Allan G, Johnston F, Finn A, Heath PT, Booy R. Severe complications of chickenpox in hospitalised children in the UK and Ireland. Arch Dis Child. 2007 Dec;92(12):1062-6. doi: 10.1136/adc.2007.123232. Epub 2007 Nov 8. PMID: 17991685; PMCID: PMC2066097.
BPSU 18th Annual report 2003 -2004
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