Varivax

Varicella vaccine, also known as chickenpox vaccine, is a vaccine that protects against chickenpox.[8] One dose of vaccine prevents 95% of moderate disease and 100% of severe disease.[9] Two doses of vaccine are more effective than one.[9] If given to those who are not immune within five days of exposure to chickenpox it prevents most cases of disease.[9] Vaccinating a large portion of the population also protects those who are n... [wikipedia]