# Herpes Zoster (HZ) Over the Past 10 Years: A Systematic Review on Trends, Triggers, and Post-COVID-19 Impact

## TL;DR

This paper reviews how the COVID-19 pandemic has affected the incidence of herpes zoster, highlighting changes in trends and risk factors over the past decade.

## Contribution

The study systematically analyzes the impact of the pandemic and vaccination on herpes zoster incidence and identifies new risk factors like psychological stress and immune dysfunction.

## Key findings

- HZ incidence increased in post-COVID-19 patients and vaccinated individuals.
- Psychological stress and immune dysfunction are potential risk factors for HZ.
- HZ cases following vaccination were reported, though causation is not confirmed.

## Abstract

Herpes zoster (HZ) is a reactivation of varicella-zoster virus (VZV), which has been traditionally associated with aging and immunosuppression. However, new data indicate that the coronavirus disease 2019 (COVID-19) pandemic has changed HZ epidemiology, with a higher incidence of HZ in post-COVID-19 patients and vaccinated subjects. This systematic review assesses the trends and triggers of HZ as well as the impact after the pandemic, focusing on the changes in the incidence rate among adult and pediatric patients during the last 10 years. All studies published between the years of 2014 and 2024 were accrued, based on a systematic review conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant articles were identified from searches of databases and other sources. Eligibility criteria of studies were applied, and qualitative and quantitative syntheses of studies were performed. A total of 11 studies were included in the review, which examined the association between COVID-19, vaccination, and HZ risk. Several studies suggested that psychological stress and immune dysfunction could be risk factors for HZ incidence. HZ cases after COVID-19 vaccination have been reported, although causation is not established. Based on countries in which COVID-19 was diagnosed, hospitalizations are estimated at 14.4 per 100,000 inhabitants (0.6 to 32.9 per 100,000), and mortality was 1.3 per 100,000, points in this IR Batch (assuming that these are of all diagnosed cases). The risk of HZ reactivation may be increased following COVID-19 infection and vaccination. Higher hospitalization rates with higher mortality risks and neurological consequences were also observed in some populations. Strengthening HZ vaccination programs and studying post-COVID-19 immune responses further can be essential for reducing long-term health risks.