Forbes H, Douglas I, Finn A, et al. - Researchers conducted a self-controlled case series study using UK electronic healthcare data to evaluate the magnitude and duration of any assumed protective effect of household exposure to a child with varicella on the relative incidence of herpes zoster in adults. They enrolled 9,604 individuals (aged ≥ 18 years) with a diagnosis of herpes zoster between 1997 and 2018. They compared the relative incidence of herpes zoster in the 20 years after exposure to a child with varicella in the household and baseline time (all other times, excluding the 60 days before exposure). They noted that the relative frequency of zoster was lower in the periods after exposure to a household contact with varicella, with modest but long-lasting protective impacts seen. The data demonstrated that exogenous boosting gives some protection from the risk of herpes zoster, but not complete immunity, as assumed by previous cost-effectiveness assessments of varicella immunization.