Hepatitis D, also known as “delta hepatitis,” is a liver infection caused by the hepatitis D virus (HDV). Hepatitis D only occurs in people who are also infected with the hepatitis B virus. Hepatitis D is spread when blood or other body fluids from a person infected with the virus enters the body of someone who is not infected. Hepatitis D can be an acute, short-term infection or become a long-term, chronic infection. Hepatitis D can cause severe symptoms and serious illness that can lead to life-long liver damage and even death. People can become infected with both hepatitis B and hepatitis D viruses at the same time (known as “coinfection”) or get hepatitis D after first being infected with the hepatitis B virus (known as “superinfection”). There is no vaccine to prevent hepatitis D. However, prevention of hepatitis B with hepatitis B vaccine also protects against future hepatitis D infection.