Chickenpox exposure and herpes zoster disease incidence in older adults in the U.S

Exposure to varicella zoster virus through close contact with people with chickenpox was suggested to boost specific immunity, reducing the risk of herpes zoster (HZ). Since the introduction of the varicella immunization program in the US in 1995, varicella morbidity has decreased substantially. This article examines incidence and risk factors associated with self-reported HZ disease and whether exposure to chickenpox within the previous decade reduces the risk of shingles in this age group.

In 2004, a national random-digit dial telephone survey was used to obtain information on self-reported HZ disease, demographic characteristics, and exposure to children with chickenpox in the past decade. National estimates of the incidence of shingles disease were calculated.

Incidence rate of self-reported HZ was 19 per 1,000 population per year. White individuals were 3.5 times more likely to report shingles than Hispanic individuals (p<0.01). Previous exposure to chickenpox did not protect against HZ disease in this population. Seven percent of adults > or =65 years of age reported exposure to children with chickenpox in the past decade.

Incidence of HZ among individuals > or =65 years of age in the U.S. may be higher than previously described in the literature, with whites being at higher risk for the disease. Currently, the potential contribution of exposure to chickenpox as a mechanism for maintaining cell-mediated immunity against HZ may be limited to a small percentage of the population. Vaccination against HZ may represent the best means of decreasing this disease burden.