Chickenpox is caused by a virus and usually spreads when a person touches chickenpox or shingles blisters — or if they breathe in the virus. You can breathe in the virus after someone with chickenpox or shingles scratches their blisters, which releases the virus into the air. It’s also possible to get chickenpox from breathing in tiny droplets from people who have it that get into the air after they breathe or talk.

Children need 2 doses of the vaccine between 1 and 6 years of age.

Adults that aren’t immune to chickenpox (if you haven’t had chickenpox in the past or you haven’t been vaccinated against it), you need to get 2 doses of the vaccine about 1 month apart.