Varicella vaccination in children.
Varicella vaccines have been developed, studied, tested and used since the early 1970s, first in Japan and subsequently in Europe, the US, Asia and South and Central America. Varicella vaccination was first used to immunise Japanese children in cancer remission, as wild-type varicella disease is often fatal in immunocompromised individuals. Since then, it has been licensed for use in healthy children as well. There are 3 manufacturers of the vaccine: Biken (Japan), Merck and Co. (US) and SmithKline Beecham (Belgium). The Biken vaccine has been approved for use in Japan since 1986 (although it was developed and used for research purposes from 1974). The Merck and Co. vaccine was approved in the US in March 1995 and the SmithKline Beecham vaccine was first licensed for use in immunocompromised children in 1984 and for healthy children in Sweden in October 1994. All 3 vaccines are derived from the Oka (Japanese) strain obtained from an immunologically normal 3-year-old Japanese boy named Oka with wild-type disease. Aventis-Pasteur has also purchased the rights to the Oka strain but no published literature is available for review. Use of the varicella vaccine has been controversial because many argue that: (i) the disease is mild and not worth preventing; (ii) the long term immunity provided by the vaccine is unknown; and (iii) the average age of those with the disease will increase if the vaccine is used and hence there will be more complications in older patients and, therefore, more costs. Because of some outbreaks of secondary bacterial infections after varicella in children in US day care centres, vaccination of healthy children is required in some states. It will be interesting to see whether other countries adopt a similar recommendation as more families have 2 working parents. The financial benefit of the vaccine (keeping parents at work) may encourage more use of the vaccine and a subsequent recommendation for immunisation schedules.
Clements
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Section of Paediatrics and Infectious Diseases, Duke University Medical Center, Durham, North Carolina 27710, USA. cleme002@mc.duke.edu