The Burden of Varicella Complications Before the Introduction of Routine Varicella Vaccination in Germany

Abstract

The true burden of varicella complications in Germany is not known. We investigated the incidence and pattern of varicella complications in children and adolescents using 3 independent surveillance sources. Prospective nationwide surveillance in all pediatric hospitals through the German Pediatric Surveillance Unit [Erhebungseinheit für Seltene Pädiatrische Erkrankungen in Deutschland (ESPED)] was used to ascertain hospitalized varicella cases in children <or=16 years of age between January 2003 and December 2004. In the federal state, North-Rhine Westphalia (NRW), a practice sentinel network [European Diabetes Study Group (EURODIAB)] and pediatric hospital based International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) surveillance were additionally used to refine incidence estimates via capture-recapture methodology. A total of 918 hospitalized varicella patients (male-to-female: 55%/45%) with a median age of 3.3 years (interquartile range, 1.4-5.2) and a median hospital stay of 5 days (interquartile range, 3-8) were reported. Varicella associated complications occurred in 80% of the hospitalizations, most frequently being neurologic (25.4%), skin infectious (23.2%), and gastrointestinal tract complications (15.0%). Most hospitalizations (77%) occurred in previously healthy children. A predisposing condition existed in 207 children (23%): immunosuppression 7%, atopic dermatitis 7%, and other underlying chronic conditions 9%. Severity of varicella complications was related to increasing age and immunosuppression. Permanent or possible sequelae were reported in 15 (1.7%) and 78 (8.7%) of all children, respectively; 10 children died. Capture-recapture analyses yielded an incidence of 14.1 (95% confidence interval, 9.7-18.6) varicella hospitalizations/100,000 children, corresponding to 1996 (95% confidence interval, 1363-2629) varicella-related hospitalizations per year in Germany. These data show that the severity of varicella complications in healthy children has been previously underestimated.