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 diving diving" has been credited to Michael Menduno, who was editor of the (now defunct) diving magazine "aquaCorps Journal". The concept and term, "technical diving", are both relatively recent advents, although divers have been engaging in what is now commonly referred to as technical diving for decades. The term "technical diving" can be traced back to the cover story of the first issue of "AquaCorps" magazine, in early 1990, titled "call it "High-Tech" Diving" by Bill Hamilton, describing the current state of recreational diving beyond the generally accepted limits, such as, deep, decompression and mixed gas diving. By mid 1991, the