 Patients will be given a total of either etanercept 50 mg subcutaneously or placebo subcutaneously at the GCRC at the end of their visit. They will receive this in two injections of 25 mg each, one given immediately following the other, at different body sites. Etanercept will be supplied as a sterile, white, preservative-free, lyophilized powder. The pharmacy will reconstitute it with 1 mL of the supplied sterile bacteriostatic water for injection BWFI, United States Pharmacopeia USP containing 0.9 benzyl alcohol. Each vial of etanercept contains 25 mg etanercept, 40 mg mannitol, 10 mg sucrose, and 1.2 mg tromethamine. Subjects will receive the 50 mg dose of etanercept or placebo once a week, given as two 25 mg injections, one immediately following the other, at different body sites, at each of their ensuing three visits to the GCRC, on Visit Day 8, Visit Day 15 and Visit Day 22. Subjects will be monitored for 30 minutes after the injection of study drug at each visit. The skin injection site will be observed and their vital signs will be taken. If a subject has a significant exposure to varicella virus during the study, transient termination of the study will be considered. 