Immunocompromised Adults at Risk of Severe Varicella

Background and Clinical Significance: Varicella, caused by the varicella-zoster virus (VZV), is typically a childhood disease; however, adult cases carry substantially higher morbidity and mortality. Immunocompromised individuals are particularly vulnerable to severe outcomes. Many adults in Japan lack documented varicella vaccination, representing a missed opportunity for preventing primary VZV infection. None of the patients had documented prior varicella vaccination. Case Presentation: We conducted a retrospective review of varicella cases at Hirosaki University Hospital between April 2007 and March 2025. Ten patients (eight adults and two children) were identified. Among the eight adult patients, written informed consent for publication was obtained from five patients, whose clinical courses are described in detail in this report. Four patients had underlying conditions requiring immunosuppressive therapy, and two were undergoing cancer treatment. All immunocompromised patients exhibited hepatic dysfunction, with elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. All patients received antiviral therapy with valaciclovir or acyclovir, and some additionally received intravenous immunoglobulin. All five adult patients in this series recovered from varicella without long-term sequelae, although one later died from unrelated causes. We additionally note that one patient later died from cerebral embolism and pneumonia, unrelated to varicella. Conclusions: This retrospective case series illustrates the vulnerability of immunocompromised adults to severe varicella and aligns with current recommendations supporting the vaccination of susceptible high-risk adults. While antiviral therapy remains essential for clinical management, prevention through appropriate vaccination strategies-varicella vaccine for preventing primary infection in eligible individuals and RZV for preventing herpes zoster reactivation in immunocompromised adults-represent an important preventive strategy for reducing overall VZV-related morbidity and mortality. These findings reinforce the importance of preventive strategies, including vaccination and early recognition of varicella in high-risk adults.