Varicella vaccine were vaccinated as children were still protected from varicella." However, since only one out of five Japanese children were vaccinated, the annual exposure of these vaccinees to children with natural chickenpox boosted the vaccinees' immune system. In the United States, where universal varicella vaccination has been practiced, the majority of children no longer receive exogenous (outside) boosting, thus, their cell-mediated immunity to VZV (varicella zoster virus) wanes—necessitating booster chickenpox vaccinations. As time goes on, boosters may be necessary. Persons exposed to the virus after vaccine tend to experience milder cases of chickenpox. Catching "wild" chickenpox as a child has been
European Centre for Disease Prevention and Control The office of the Chief Scientist oversees the seven Disease Programmes, the Microbiology Coordination Section and the Scientific Advice Coordination Section. The Disease Programmes focus on specific disease groups: Two shared-resource units – Surveillance and Response Support, and Public Health Capacity and Communication – provide specialist expertise. The Information and Communication Technologies Unit provides infrastructure, application development and support. The Resource Management and Coordination Unit controls ECDC’s human and financial resources. ECDC publishes numerous scientific and technical reports covering various issues related to the prevention and control of communicable diseases. Comprehensive reports from key technical and scientific meetings are also