Universal varicella vaccination

• Decreased varicella mortality in all age groups except those aged ≥ 50 years (average varicella deaths per year: 145 in 1990–1994 versus 66 in 1999–2001).1

• Decreased varicella cases in all age groups, with a non-significant reduction in hospitalisations (average annual hospitalisations in three surveillance regions: 40 before vaccination versus 14 after vaccination).2

US data on herpes zoster have not yet been published.

There are concerns that, in the longer term, universal varicella vaccination may increase the incidence of adult varicella and herpes zoster, similar to the effect of pertussis vaccination on adult pertussis. Modelling in the United Kingdom predicted that universal infant vaccination would initially reduce varicella, but would result in increases in herpes zoster 5–10 years later and adult varicella 20–40 years later.3 In contrast, modelling of adolescent vaccination predicted a small decrease in varicella, but no increase in later adult varicella.3

Varicella is generally perceived as a mild illness, while vaccination is largely valued for preventing serious, life-threatening conditions. Anecdotal reports of low levels of private purchase of VZV in Australia suggest it may not be a priority for some families. With 36% of general practitioners concerned about unknown side effects of VZV,4 and public concern about vaccine adverse events in the face of low disease rates, the level of acceptance of universal varicella vaccination by providers and consumers is uncertain.

Alternatives to universal varicella vaccination were a high-risk strategy (vaccination of children with chronic illness and family members of high-risk individuals) or waiting until US disease patterns were established. These were real options as:

• A high-risk strategy may prevent up to 45% of paediatric hospitalisations.5

• Hospitalisation and herpes zoster contribute more to health costs than treatment in the community or acute varicella.5

• Natural infection, at the cost of disease, immunises most of the population.

Any increase in adult varicella and herpes zoster caused by varicella vaccination may be alleviated by booster doses, but the added cost, difficulty in reaching the target population, and potential impact on community confidence in vaccination may be significant problems. The universal varicella vaccination program will test providers’ and consumers’ acceptance of vaccination against what is perceived as a mild illness.