Smallpox is characterized by a rash and fluid-filled blisters. There are two variants of the disease with the more severe version resulting in a mortality rate of between 30-40%, while the minor form of the virus exhibits a mortality rate of around 1%.

The variola virus causes smallpox and is transmitted through air-borne particles secreted from the mucous membranes and cough of an infected person thus making it extremely contagious. The smallpox vaccination is required within three days of exposure and will result in a greatly reduced risk of the virus taking over the body. However, vaccination after the initial three day period will produce some form of protection and will modify the severity of the disease.