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
Technical change of capitalism (including creative destruction) is the subject of great contention by adherents of other systems of macroeconomic organization who see the end-result of obsolescence as the creation of a permanent underclass that has an unequal level of access to capital investment, educational resources that are not necessarily of their own making, while others seek to create an equal outcome for disproportionate labor or capital inputs that have not as yet been able to demonstrate a viable model that can compete against free-market economies on a near-term or long-term basis. Technical change A technical change is a term used in