Herpes zoster (HZ) affects almost 1 in 3 adults in the United States during their lifetime. The disease often causes severe pain that may last for a few weeks, with substantial influence on individuals’ quality of life, daily activities, and work. Some patients continue to experience debilitating pain for more than a year, a complication that is known as postherpetic neuralgia (PHN). Serious cases can involve the eyes and central nervous system disease.
The HZ incidence increases sharply with age. For example, the incidence is 4.6 cases per 1000 person-years in those who are aged 50 to 59 years, and the rate increases to 10.3 cases per 1000 person-years in those who are 80 years or older. In addition, several observational studies demonstrate an upward trend in age-specific incidence of HZ.1 The underlying cause of the upward trend is debated.