The Effectiveness of Varicella Vaccination in Children in Germany

Inclusion Criteria: * Male or female child at least one year of age, born on or after July 1 2003. * Residence in Germany * At least one previous well-child visit to the practice * Written informed consent obtained from parents/guardians of the subject as per local requirements. * Specific inclusion criterion for cases: * Suspected primary varicella disease (i.e. chickenpox) at the time of study entry Exclusion Criteria: * Ineligible for varicella vaccination, due to any medical contraindication. These contraindications are: * History of hypersensitivity to any of the components of the vaccines * Congenital or acquired immunodeficiency * Treatment with immunosuppressive therapy * HIV-infected patients, when CD4 \< 25% of total lymphocytes * Previous history of chickenpox by physician record or parental report. * Lack of documented vaccination history (written or computerised practice records or child's vaccination card/booklet).