# Herpes Zoster in Children in the Post-Vaccination Era: Age Shift, Clinical Characteristics, and Changing Dermatomal Patterns

## TL;DR

This study shows that childhood herpes zoster is occurring at younger ages and with different patterns since the introduction of the varicella vaccine.

## Contribution

The study identifies a younger age of onset and distinct dermatomal patterns in vaccinated children with herpes zoster.

## Key findings

- Vaccinated children developed herpes zoster at a younger age compared to those with natural varicella.
- Cervical dermatome involvement was more common in younger vaccinated children.
- HZ in vaccinated children was typically self-limiting with rare complications like postherpetic neuralgia.

## Abstract

Background: Universal varicella vaccination has fundamentally altered the epidemiology of varicella-zoster virus (VZV) infections. While the incidence of primary varicella has declined, the characteristics of herpes zoster (HZ) in the post-vaccine generation remain a subject of debate. This study aimed to analyze the demographic and clinical characteristics of pediatric HZ in the context of a mature national immunization program. Methods: This retrospective observational study included children under 18 years of age diagnosed with HZ between 2018 and 2025 at the dermatology outpatient clinic of a tertiary hospital. Demographic, clinical, and epidemiologic variables were retrieved from hospital records. Results: A total of 64 pediatric patients (mean age: 10.5 ± 4.9 years; 59.4% male) were analyzed. The majority (93.8%) were vaccinated. Vaccinated children presented at a significantly younger age (mean: 9.1 ± 5.4 years) than those with a history of natural varicella infection without vaccination (mean: 12.3 ± 3.5 years; p = 0.007). The thoracic (39.1%) and cervical (35.9%) dermatomes were most frequently affected. Cervical involvement was significantly more frequent in younger children (mean age 7.1 years), whereas thoracic and lumbar dermatomes predominated in adolescents (mean age > 12 years; p = 0.001). Seasonal distribution was even, but the annual frequency peaked in 2023, whereas 2021 showed the lowest number. Only one patient (1.6%) developed postherpetic neuralgia, and no other complications were observed. Conclusions: Universal vaccination is associated with a shift in the onset of pediatric herpes zoster to younger individuals, often presenting with cervical dermatomal involvement hypothesized to be linked to vaccination injection sites. Clinicians should recognize that while HZ in vaccinated children is typically a self-limiting event that does not require an extensive immunologic workup in otherwise healthy, immunocompetent children, rare complications like postherpetic neuralgia can still occur. Limitations of this sin-gle-center, retrospective study include a high exclusion rate due to missing data, a small number of unvaccinated comparators, and the lack of viral genotyping to differentiate wild-type from vaccine-strain virus.