| | Vaccines, Immunization and Biologicals |
 | | The duration of protection against varicella and zoster without natural exposure to the virus, the epidemiological impact of childhood vaccination at various levels of coverage, and the zoster-preventive effect of vaccination of adults and elderly people with a history of varicella need to be better understood. |
 | | Varicella vaccine may be used either at an individual level to protect susceptible adolescents and adults, or at a population level, to cover all children as part of a national immunization programme. |
 | | Varicella vaccines based on the attenuated Oka-strain of VZV have been marketed since 1974, and the positive results of extensive safety, efficacy and cost- effectiveness analyses have warranted the introduction of these vaccines into the childhood immunization programmes of several industrialised countries. |
| www.who.int /vaccines-diseases/diseases/PP_Varicella.shtml (3559 words) |