What is chickenpox?

Chickenpox (varicella) is a very contagious and common viral infection. Chickenpox infections occur year-round, but most occur during the winter and spring months. Most people are first exposed to chickenpox during early childhood. In otherwise healthy children, chickenpox usually is not a serious illness, although its severity can vary from person to person. Chickenpox in teenagers, adults, and people with immune system problems usually is more severe and more likely to cause complications.

What causes chickenpox and how is it spread?

Chickenpox is caused by the varicella-zoster virus, which is a type of herpes virus. The virus is spread much like a cold–it usually enters through your respiratory tract after an infected person sneezes, coughs, or shares food or drinks. Similarly, you can get infected with chickenpox if the virus gets on a your hands and you don't wash them before you touch your mouth or face. Chickenpox can also spread from skin-to-skin contact when open sores develop. A person infected with chickenpox can spread the virus before they develop any symptoms.