The Varivax vaccine is given to prevent Chicken pox, a common viral exanthem (viral rash) seen commonly in childhood in the past. The vaccine is approximately 85% effective in preventing chicken pox after one dose. Therefore, two doses of Varivax are given to confer excellent prevention of Chicken Pox at 98%, but 100% protection against severe varicella. The second dose is given at 4 years of age. Since beginning the national Chicken pox vaccination program, the incidence of Chicken pox has fallen dramatically. Side effects of the vaccine are quite rare and include the development of a few small vesicles on the skin (these look like chicken pox lesions) which resolve over a few days. The vaccine does not prevent the occurrence of Shingles (see section on Chicken pox in this handbook), but does make it less likely to occur.
Chicken pox Vaccine CDC Information Sheet: Varivax VIS