The incidence of shingles and its implications for vaccination policy.

A vaccine is now available to prevent varicella-zoster infection, but its place in routine preventive care is not yet determined. The age specific incidence of shingles was examined separately by gender and age groups (15-24, 25-44, 45-64, 65-74 and 75 years and more) over the years 1994-2001. These incidence data were applied to national available data for the UK on current life expectancy to calculate the risk of shingles infections at varying ages. The potential benefit of an effective vaccine was estimated using three models of vaccine efficacy applied separately to males and females at ages 50, 60 and 65 years and assuming vaccination at a single age. Similar calculations were made using a two dose strategy at age 45 and 65 years and at age 50 and 70 years. The cost per case saved was estimated from a vaccination cost of pound 40 per dose. The probability of having had an attack of shingles before age 45 years is 8.6% for males and 10.5% for females, The risk of acquiring shingles over an expected lifetime (assuming no preventive vaccination) for males aged 45 years is 22% and for females 32%. Whichever vaccine efficacy model was chosen, a single vaccination policy at age 65 years was the most favourable option in both males and females. A two age vaccination policy was estimated to increase the cost per case saved by 30% over a single age policy but administration at age 50 and 70 years substantially increased the number of cases saved as compared with a single age policy and was potentially better than vaccination at 45 and 65 years.