Chickenpox (varicella) is a highly infectious disease that typically causes a widespread rash which commonly results in scarring. It can also cause patients to feel generally unwell and have a fever. Symptoms are usually mild in young children but the likelihood of more severe symptoms, including pneumonia, increases with age. Infection during pregnancy has risks for the mother and the unborn child.

There are two vaccines available - Varilrix and Varivax. The two vaccines can be used interchangeably, so a vaccination course started with one brand can be completed with the other.