# Seroprevalence of Varicella-Zoster Virus and the Need for Herpes Zoster Vaccination Among Adults in Saudi Arabia

## TL;DR

This study finds high immunity to varicella-zoster virus in Saudi adults but highlights low vaccination rates for shingles, suggesting a need for better public health efforts.

## Contribution

The study provides the first detailed seroprevalence data for VZV in Saudi adults and highlights gaps in herpes zoster vaccination.

## Key findings

- 81.1% of Saudi adults were serologically immune to VZV.
- Immunity was higher in males and older participants.
- History-based immunity assessment had limited validity, emphasizing the need for serological testing.

## Abstract

Introduction: Chickenpox is caused by the varicella-zoster virus (VZV), which can reactivate later in life, leading to herpes zoster (shingles). The varicella vaccine has been integrated into childhood immunization programs in certain regions, contributing to the control and prevention of the disease. However, there remains uncertainty regarding the seroprevalence of varicella among adults, as well as concerns about vaccination rates and public awareness of its importance.

Objective: The objective of this study is to estimate the seroprevalence of varicella among Saudi adults who may require vaccination against varicella and herpes zoster.

Methods: This descriptive cross-sectional study involved 209 Saudi adults aged 18 years and older in Riyadh. Data were collected using a validated questionnaire and serological testing for VZV-IgG antibodies. Statistical analyses were conducted to explore the relationships between seroprevalence, vaccination history, and demographic factors.

Results: The study, comprising primarily young adults aged 18-47 years (83.3%) with a nearly equal gender distribution (52.2% male, 47.8% female), found that 81.1% of participants were serologically immune to VZV. Immunity was higher among males (84.4% vs. 79% in females) and older participants (89.7% in those ≥38 years vs. 78% in those <38 years). A positive history of varicella infection or vaccination increased the likelihood of VZV-IgG positivity by nine times compared to deniers and four times compared to unsure participants. History-based immunity assessment had a sensitivity of 87.1% and specificity of 57.7%.

Conclusion: The study highlights a high prevalence of serological immunity to VZV among Saudi adults. While a positive history strongly predicted immunity, the limited validity of history-based assessments underscores the need for serological confirmation in some cases. Despite widespread immunity and consequently the risk of herpes zoster, the low uptake of herpes zoster vaccination among eligible individuals with a history of shingles points to a gap in preventive healthcare. These findings emphasize the importance of targeted public health efforts to improve vaccination coverage among adults, particularly for herpes zoster.