You are at risk for chickenpox if you have not had chickenpox or the vaccine and you:

• Live with someone who has chickenpox.
• Work or play indoors for more than 1 hour with someone who has chickenpox.
• Are in the hospital and share a room with someone who later develops chickenpox or are cared for by a staff member who later develops chickenpox.
• Have an impaired immune system.

Your risk of getting chickenpox is especially high if you are exposed to a household member with chickenpox, because of the close contact. In addition, you may develop a more severe case than the person who infected you. Chickenpox is most contagious from 1 to 2 days before the rash appears until the blisters have dried and formed crusts.

If you get a chickenpox vaccination, you are contagious only if you develop blisters. You remain contagious as long as new spots continue to develop and until all blisters have crusted over.

Some people also are at increased risk of developing complications from chickenpox, such as newborns, teenagers, adults-especially pregnant women-and those with impaired immune systems.

After you have had chickenpox, you become immune to the virus. It is possible that you may have a slight reaction after re-exposure, such as a few spots and a slight fever. However, you will not get a full-blown case of chickenpox more than once.