Prospective surveillance of varicella-zoster virus infections in an out-patient setting in Switzerland.

Limited data are available on the clinical impact of varicella in the ambulatory setting. Our goal was to determine real-life data on the clinical outcomes, medical management, and resource utilization in patients with varicella in Switzerland, a country without a universal immunization program against varicella. A total of 236 patients (222 = 94 % primarily healthy individuals) with a clinical diagnosis of varicella were recruited by pediatricians and general practitioners. Age range of patients was 0 - 47 years with a median of 5 years. The great majority of patients (179 = 76 %) were <or=6 years of age. 134 (57%) patients were single cases and in the remaining 102 patients a total of 112 further cases of varicella occurred in their households. Of these, 17 (15%) were primary cases, 18 (16%) were co-primary cases, 75 (67%) were secondary cases, and 2 cases (2%) were not directly linked to the index case. A total of 29 complications were observed in 26 (11%) of 236 patients, none of them with a known underlying disease and all subsided without apparent sequelae. All complications occurred in children under 12 years of age. In conclusion, this study describes the spectrum of varicella in an out-patient setting with a sizeable rate of complications and raises the question of the value of prophylactic immunization.