Background: Although primary Varicella-Zoster-Virus (VZV) infection generally causes uncomplicated illness confined to skin and mucous membrane among healthy children, it infrequently causes life-threatening infection especially among immuno-suppressed hosts or young infants. Limited information is available regarding the clinical features, outcomes, and the financial burden incurred by severe primary varicella infection in Thai children who required hospitalization.
Objective: To determine clinical characteristics particularly the disease severity, prevalence of complication, case fatality rate, and use of healthcare resources in terms of length of stay as well as direct medical cost of varicella associated hospitalization in children.
Material and Method: A retrospective descriptive study was conducted among children aged one month to 18 years who were hospitalized with chickenpox between 2007 and 2011 at the Queen Sirikit National Institute of Child Health, Bangkok, Thailand. Information on clinical manifestations, complications, and outcomes were obtained by medical record abstraction, and data on hospital charges were obtained from the hospital financial database.
Results: A total of 101 cases of chickenpox were identified, with a median (interquartile range IQR) age of 4 (0.8, 7.25) years. Underlying predisposing conditions for severe varicella infection were identified in 35 cases (34.7%). Seventy four of 101 (73.3%) patients developed complications, with skin and soft tissue infections being the most common (50.5%), followed by pneumonia (12.7%) and neurological complications (6.4%). There were no fatal cases. Median (IQR) duration of hospitalization and hospital charges were 6 (3, 9) days and US$ 330.2 ($139.3, $1,013.5), respectively. Children with predisposing conditions for severe varicella were significantly older, incurring 6-fold higher hospital charges and 2-fold longer hospitalization compared to their counterparts.
Conclusion: The high rate of complicated varicella and financial burden reported in this study suggested that the severity of varicella complications in children might have been previously underestimated. This study provides relevant information regarding the burden of hospitalized varicella infection among both otherwise healthy children as well as children with predisposing immuno-suppression.

Keywords: Hospitalization, Chickenpox, Pediatrics, Thailand, Varicella-zoster virus (VZV) infection