Notes from the field: severe varicella in an immunocompromised child exposed to an unvaccinated sibling with varicella--Minnesota, 2011.

Varicella usually is a self-limited disease but can result in serious complications (e.g., encephalitis, pneumonia, sepsis, hemorrhagic varicella, and death), especially among immunocompromised persons. Implementation of the varicella vaccination program in the United States, beginning in 1995, has led to declines of >95% in varicella-related hospitalizations and deaths among populations routinely vaccinated (1).