Should all adults with varicella be prescribed antiviral treatment?

Following the inclusion of a single dose of varicella vaccine in the National Immunisation Program Schedule in 2005, the incidence of varicella (chickenpox) and its complications appears to be declining, with the total number of hospitalisations per year in Australia probably now around 400–500.1 Similar trends have been observed in the United States. In spite of the immunisation program, around 5%–10% of adults in Australia remain non-immune to varicella infection. The disease may lead to significant morbidity and mortality in otherwise healthy adolescents and adults. The main potentially serious complication is pneumonitis, particularly in people who smoke and pregnant women.

There is anecdotal evidence that otherwise healthy adolescents and adults presenting to emergency departments (EDs) with varicella are likely to receive an antiviral drug, but the same is not true in general practice. In the latest version of Therapeutic guidelines: antibiotic there is no recommendation for early (oral) antiviral therapy for all adults with varicella.2 This is of concern if one considers the fact that antiviral therapy is most effective when started early in the course of varicella and is likely to reduce the rate and severity of complications.3 Guidelines in the US and the United Kingdom, on the other hand, recommend antiviral therapy for early, uncomplicated varicella in adolescents and adults.4-6 Additional benefits of treating varicella potentially include reducing demands on EDs, decreasing the risk of transmission to nonimmune individuals (particularly immuno-compromised patients) and a cost-benefit to the taxpayer.

The Pharmaceutical Benefits Scheme indications for aciclovir (or the alternative antiviral drugs) in its various orally active forms do not include varicella. Aciclovir is expensive in Australia when purchased at retail pharmacies without an authority prescription, costing $85–$135 for 35 generic aciclovir 800 mg tablets.

A formal Australian recommendation for antiviral therapy without the backing of public funding would likely compromise GP management of acute varicella cases. Given the low and decreasing incidence of varicella in the adolescent and adult population, a funded recommendation would lead to little overall cost incurred by the taxpayer — but would possibly save several Australian lives each year.