From Red Book 2006 Edition
Duration of Immunity
"Although there has been concern about waning immunity, follow-up evaluations of children immunized during prelicensure clinical trials in the United States indicate protection for at least 11 years. Studies in Japan indicate protection for at least 20 years. However, these studies were conducted during a period when a substantial amount of wild-type VZV was present in the community, with many opportunities for boosting of immunity by subclinical infection in immunized people. Experience with other live-virus vaccines (eg, measles, rubella) suggests that immunity remains high throughout life; the primary reason for second doses of measles vaccine is to induce protection in children without an adequate response to the first dose, not because of waning immunity. Follow-up studies of clinical trials in children and postlicensure surveillance studies are being performed to determine the need, if any, for additional doses of Varicella vaccine. "
"Although there has been concern about waning immunity, follow-up evaluations of children immunized during prelicensure clinical trials in the United States indicate protection for at least 11 years. Studies in Japan indicate protection for at least 20 years. However, these studies were conducted during a period when a substantial amount of wild-type VZV was present in the community, with many opportunities for boosting of immunity by subclinical infection in immunized people. Experience with other live-virus vaccines (eg, measles, rubella) suggests that immunity remains high throughout life; the primary reason for second doses of measles vaccine is to induce protection in children without an adequate response to the first dose, not because of waning immunity. Follow-up studies of clinical trials in children and postlicensure surveillance studies are being performed to determine the need, if any, for additional doses of Varicella vaccine. "
From April 2007, requirements for vaccination has changed due to break through chicken pox with one shot, the latest recommendation is as follows: first dose between 12- 15 months and second is three months from the first dose. There is a third dose between 4- 5 years of age.
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