Varicella zoster virus infection and reactivation in a psychiatric ward during the COVID-19 pandemic: a case series analysis.

Severe mental illness (SMI) may increase susceptibility to varicella zoster virus (VZV), but VZV epidemiology in psychiatric wards is poorly described. We reviewed 54 women with SMI in a closed 50-bed psychiatric ward (July 2021-December 2024) and identified 3 varicella and 2 herpes zoster cases during April-October 2023. The varicella attack rate among exposed susceptibles was 6.38%, and herpes zoster incidence was 12.41 per 1,000 person-years. All case patients had received coronavirus disease 2019 vaccination and had prior severe acute respiratory syndrome coronavirus 2 infection. These findings highlight infection-control challenges, immune vulnerabilities, and prevention gaps in long-term psychiatric settings.