Chickenpox

Chickenpox (varicella) is a highly contagious infectious disease caused by the varicella-zoster virus. The virus causes an itchy blister-like rash, fatigue (tiredness), and fever. It can be especially serious in babies, older adults, and people who have weakened immune systems.

Chickenpox spreads easily through coughing and sneezing. It can also be spread by touching or breathing in particles from chickenpox blisters. The chickenpox vaccine is very effective at preventing chickenpox. For people who do get infected with chickenpox even though they’ve been vaccinated, the vaccine helps make the chickenpox symptoms less severe.