# Epidemiology of herpes zoster and postherpetic neuralgia in Japan: analysis of a large-scale claims database

## TL;DR

This study analyzed HZ and PHN incidence in Japan from 2014 to 2023, finding rising rates with age and seasonal patterns.

## Contribution

The study provides comprehensive epidemiological data on HZ and PHN in Japan to guide vaccination strategies.

## Key findings

- HZ incidence increased with age, reaching 18.81 per 1,000 person-years in those aged ≥80 years.
- PHN risk was higher in older individuals, with rates increasing from 0.37 to 2.98 per 1,000 person-years.
- HZ incidence was higher in summer and not strongly linked to varicella incidence.

## Abstract

Herpes zoster (HZ) is a global public health concern. Although HZ vaccination is expected to reduce both HZ and its complications, comprehensive epidemiological data to guide vaccination strategies are scarce.

We conducted a large-scale analysis of a claims database in Japan to examine standardized incidence rates of HZ and postherpetic neuralgia (PHN) from April 2014 to March 2023. We also evaluated the risks of hospitalization and PHN after HZ, and analyzed varicella incidence using national surveillance data.

The overall standardized incidence rates were 9.58 and 1.00 per 1,000 person-years for HZ and PHN, respectively. From 2014 to 2023, these rates increased, with estimated annual percent changes of 1.16% (95% confidence interval, 0.52–2.00) for HZ and 0.99% (0.09–3.04) for PHN. The incidence of HZ increased steadily with age: 7.17 in the 40–49 age group, 9.73 in the 50–59 age group, 13.96 in the 60–69 age group, 17.99 in the 70–79 age group, and 18.81 in those aged ≥ 80 years. The effect of aging was more pronounced for PHN, with corresponding rates of 0.37, 0.78, 1.78, 2.97, and 2.98, respectively. The overall risks of hospitalization and PHN following HZ were 4.8% and 10.4%, respectively, with risk ratios approximately 2–3 times higher in those aged ≥ 70 years than in those aged 50–59. HZ incidence was higher in summer and showed little association with varicella incidence.

Our findings provide evidence to inform individuals and policymakers in developing strategies to prevent HZ and its complications.

The online version contains supplementary material available at 10.1186/s12879-026-12534-0.