Complicated varicella

Complicated varicella denotes varicella caused by primary infection with varicella-zoster virus that is accompanied by complications such as bacterial skin and soft-tissue infection, pneumonia, or central nervous system involvement ^[1][2]. The virus is a DNA herpesvirus that remains latent in sensory nerve ganglia after primary infection ^[1].

A mild prodrome of fever and malaise may precede rash onset, especially in adults, whereas children often present with rash first ^[1]. The exanthem rapidly evolves from macules to vesicles and crusts in unvaccinated persons ^[1]. Documented complications include bacterial skin and soft-tissue infection in children and pneumonia in adults ^[1], and in a pediatric series, central nervous system manifestations such as encephalitis and cerebellar ataxia, disseminated infection with multi-organ involvement, and glomerulonephritis with superinfection were observed ^[2].

Before vaccine introduction in the early 1990s, varicella was very common in the United States, with over 90% of cases, 70% of hospitalizations, and about half of deaths occurring in children ^[1]. Vaccination has substantially reduced varicella illness, hospitalizations, and deaths, although infections and complications still occur ^[1]. Complication patterns vary by age, with bacterial skin and soft-tissue infection common among children and pneumonia common among adults ^[1].

Varicella-zoster virus spreads person to person through direct contact, inhalation of aerosols from vesicular fluid of skin lesions in acute varicella or zoster, and possibly infected respiratory secretions ^[1]. Contagiousness begins 1 to 2 days before rash onset and continues until all lesions have crusted, or until no new lesions appear for 24 hours in vaccinated persons ^[1]. Approximately 90% of susceptible close household contacts develop infection after exposure ^[1].

Routine varicella vaccination has substantially reduced illness, hospitalizations, and deaths in the United States ^[1]. Two vaccine doses are associated with less frequent breakthrough varicella than a single dose ^[1]. In children with cancer, reducing exposure among seronegative individuals is important, and postexposure prophylaxis with varicella-zoster immune globulin is generally protective against severe and complicated varicella, though some centers use oral aciclovir despite limited controlled immunocompromised data ^[3]. Vaccination of healthy susceptible family contacts of pediatric malignancy patients is supported, but not patient self-administration ^[3].

1. 1 US Centers for Disease Control and Prevention. Clinical Overview of Chickenpox (Varicella) | Chickenpox (Varicella) | CDC [Internet]. cited 23 Oct 2026. Available from: https://www.cdc.gov/chickenpox/hcp/clinical-overview/index.html
2. 2 Phuah HK et al. Complicated varicella zoster infection in 8 paediatric patients and review of literature. Singapore Med J. 1998 Mar. PMID: 9632970. PubMed: https://pubmed.ncbi.nlm.nih.gov/9632970/
3. 3 Fisher JP et al. Preventing varicella in children with malignancies: what is the evidence? Curr Opin Infect Dis. 2011 Jun. PMID: 21455062. doi: 10.1097/QCO.0b013e328345d666. PubMed: https://pubmed.ncbi.nlm.nih.gov/21455062/