In the great majority of cases, it is a mild disease.

Complications are rare but do occur. They include skin superinfection, pneumonia, encephalitis and other central nervous system manifestations.

The risk of hospital admission (used as a marker of severe disease) and death depends on age (slide). It is lower in children (ages 1-14 years), higher in infants and young adults and considerably higher in older age-groups.

(Source of data: Fairley CK, Miller E. Varicella-zoster virus epidemiology - a changing scene? J Infect Dis 1996; 174(Suppl 3):S314-9.)