Efforts to develop a hepatitis C vaccine started decades ago, when the hepatitis C virus was identified. Since then, researchers have studied several possible vaccines in animals. Some of these vaccines have undergone limited testing in people.

Progress on developing a successful vaccine has been slow. Reasons for that include the virus itself and the animal models.

The unique characteristics of the virus

The hepatitis C virus is more variable than the hepatitis A and hepatitis B viruses. Hepatitis C occurs in at least seven genetically distinct forms, called genotypes, with multiple subtypes. About 60 subtypes have been identified.

Different genotypes cause infections in different parts of the world. A global vaccine would have to protect against all variants of the virus.

Limited animal models of hepatitis C infection

A hepatitis C infection in chimpanzees is similar to an infection in humans. But ethical and cost concerns limit medical research with these animals.

Although researchers are working to develop an effective vaccine, new medicines can cure nearly everyone who has hepatitis C.