Primary varicella and herpes zoster among HIV-infected children from 1989 to 2006

Abstract

Objectives: The primary objective of this study was to determine the incidence of herpes zoster in perinatally HIV-infected children. Secondary objectives included assessing the impact of highly active antiretroviral therapy and varicella zoster virus immunization on primary varicella and herpes zoster incidence and identifying risk factors for herpes zoster. We hypothesized that the incidence of herpes zoster has decreased in this population as a result of highly active antiretroviral therapy and routine varicella zoster virus immunization.

Patients and methods: This retrospective cohort study included HIV-infected children at a pediatric HIV clinic from 1989 to 2006. Incidence rates for 3 intervals (1989-1996, 1997-1999, and 2000-2006) were compared on the basis of introduction of highly active antiretroviral therapy (1996) and varicella zoster virus vaccination (1999). A Cox proportional-hazards regression model was developed for the time to herpes zoster among the subset of patients with primary varicella infection.

Results: In 356 patients followed for 1721 person-years, the incidence of herpes zoster according to period was 30.0 per 1000 person-years in 1989-1996, 31.9 per 1000 person-years in 1997-1999, and 6.5 per 1000 person-years in 2000-2006. There was no difference in incidence-rate ratio between 1989-1996 and 1997-1999. However, there was a significant difference in herpes zoster incidence when comparing 1989-1999 with 2000-2006. The incidence of primary varicella zoster virus infection and herpes zoster in the 57 patients who received the varicella zoster virus vaccine was 22.3 per 1000 and 4.5 per 1000 person-years, respectively. Highly active antiretroviral therapy at the time of primary varicella zoster virus infection was protective against herpes zoster and increased herpes zoster-free survival.

Conclusions: The incidence of herpes zoster has decreased since 1989. The decline occurred after 2000, likely representing the combined effect of immunization and highly active antiretroviral therapy. The use of highly active antiretroviral therapy at the time of primary varicella zoster virus infection decreased the risk of herpes zoster and increased herpes zoster-free survival. Varicella zoster virus immunization was effective in preventing both primary varicella zoster virus and herpes zoster in this cohort.