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
International Society for Disease Surveillance biosurveillance. Every year, the ISDS conference draws over 350 professionals from a broad range of disciplines to learn the latest achievements, analytic methods, best practices, conceptual frameworks, and technical innovations in the rapidly evolving field of disease surveillance. The ISDS conferences provide fertile ground for cultivating new ideas and partnerships by bringing together local, state, and federal public health practitioners, academic researchers, clinicians, policymakers, and decision makers from governmental and nongovernmental entities. The 12th annual conference was held in December 2013, in New Orleans, LA. The theme for the 2013 conference—Translating Research and Surveillance into Action—highlighted one of the salient