Efficacy of postexposure immunization with live attenuated varicella vaccine in the household setting - A pilot study

The aim of the present study was to examine the efficacy of postexposure vaccination with Varilrix® in the household setting. A randomized, double-blind, placebo-controlled design was used. Twenty-two children received the varicella vaccine and 20, a placebo. The relative risk of developing varicella with a placebo compared with the vaccine was 1.1 (95% confidence interval 0.55-2.21). The risk of developing moderate to severe disease was eight times greater in the placebo group (RR = 8), indicating an 80% protective effect against moderate/severe disease. The varicella vaccine Varilrix® may not be effective in preventing varicella when administered after household exposure, although it is highly effective in ameliorating the disease in those who acquire it under these circumstances.