Chickenpox is caused by the highly contagious varicella-zoster virus and is transmitted through the air as well as through skin-to-skin contact. E.R. physician Dr. Travis explains how chickenpox infects the body.

Ninety percent of chickenpox infections occur during childhood, but adult infections have serious ramifications. To prevent contracting the virus, adults can get vaccinated. Some adults may already be immune to chickenpox if they carry the antibodies, which can be determined through a blood test.

"Pregnant women should see if they're immune to it," Dr. Lisa advises. "Because it's really bad if they get it when they're pregnant, and then they should wait three months until after they get the vaccine [to get pregnant.]