Family history of zoster and risk of developing herpes zoster

Abstract Background Studies have investigated a possible association between family history of HZ and the occurrence of HZ. However, the results were inconclusive and susceptible to bias. We evaluated this association in an elderly population. Methods The matched case-control study conducted at Kaiser Permanente Southern California in 2012-2015 included 656 incident HZ patients ≥60 whose skin lesion tested positive for varicella zoster virus by polymerase chain reaction. Half of the HZ patients were vaccinated with zoster vaccine as achieved by stratified sampling. The controls were randomly selected and 1:1 matched to the cases on sex, age (±1year), and zoster vaccination (±3 months of the case's vaccination date). Conditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI). Results Having any blood relative with a history of HZ was associated with a slightly increased risk of HZ (adjusted OR=1.37, 95% CI 1.05–1.79). The adjusted OR associated with having one and two categories of first-degree blood relatives with a history of HZ was 1.30 (95% CI: 0.97–1.73) and 2.53 (95% CI: 1.17–5.44), respectively. Conclusions Our results suggested a weak association between the development of HZ and a positive family history of HZ among the elderly population.