Varicella in the normal and immunocompromised host

Infections from VZV in the 1990s are ubiquitous and represent a significant impact in health care resources utilized and on the individual with disease. The last several decades have brought many changes in management, including induction of passive immunity (V21G), active immunization (LAVV), and treatment with antiviral medications, as well as active research for improved antivirals. Following licensure of several Oka strain LAVVs in several countries in the Far East, Europe and the United States, the vaccine has been administered to several million individuals. The vaccine has been generally well tolerated, with the most common complaints being pain and redness at the injection site and a mild rash following vaccination. The incidence of HZ is not increased in vaccinees and may be decreased. Efficacy rates vary between 65 and 100%, depending on the intensity of exposure to natural varicella and the potency of the vaccine. In those few vaccinees who develop MVLS, the rash is generally milder than that seen following natural infection. There has been no evidence to date to indicate waning immunity post-vaccination. Studies are in progress in the United States to evaluate whether this will occur and the effect of booster doses of vaccine. Active research continues to create improved antiviral medications, focusing on increased bio-availability, longer half-lives, increased safety and overcoming antiviral resistance. At present there is no consensus of when and how the newer antivirals will replace acyclovir.