When the hepatitis C virus (HCV) enters a person’s bloodstream, it 'seeks out' the way to the liver and penetrates the liver cells. Once there, it begins to reproduce. The virus uses the liver cells to multiply, but does not harm it directly. The immune system then detects the cells infected with the virus and destroys them. The liver becomes inflamed, which is a sign that the liver cells are being destroyed. This is an acute hepatitis C infection.

Not everyone exposed to HCV will contract the infection. This depends on the amount of virus transmitted. The virus is most likely to be transmitted as a result of exposure to blood. Any contact with infected blood should be avoided.

If the immune system kills all the infected cells, and thus clears the virus, this is described as spontaneous clearance. Between 20 and 50% of people who have the virus manage to overcome acute hepatitis C in this way. Antibodies against the virus remain behind after the infection has been cleared. Some studies have found higher likelihood of spontaneous clearance in women, white people, people with hepatitis B virus co-infection, and those with acute HCV infection symptoms (possibly because this indicates a stronger immune response); and lower likelihood in men, black people, heavy alcohol users, and those with HIV co-infection.^{1 2 3}

However, in most people (up to 80%), hepatitis C becomes chronic. The infection is described as chronic if the virus remains in the body for longer than six months and the HCV RNA in the blood is still positive. In cases of chronic hepatitis C, the immune system has not managed to detect and eliminate all the infected cells completely. In chronic infection, the virus continues to cause inflammation of the liver, which also leads to the destruction of healthy cells. The long-lasting inflammation gradually leads to scarring of the liver tissue.

In the final stages of hepatitis C, healthy liver tissue is largely replaced by hardened scar tissue. This state is called cirrhosis.

Once hepatitis C has become chronic, medical treatment is the only possible cure. However, as the processes described largely go unnoticed by the majority of people with hepatitis C, it can often take years or even decades until hepatitis C infection is diagnosed.

This long period of ‘silent’ infection is part of what makes chronic hepatitis C such a threat to a person’s health. The acute phase often progresses without any symptoms, or only non-specific symptoms occur. The chronic phase is rarely accompanied by any definite symptoms.⁴ As it goes unnoticed by the person living with the virus, it can lead to liver damage. Diagnosis often only happens late and by chance. By this point, complications, such as fibrosis or cirrhosis of the liver, may have already occurred. The extent of liver damage is a shock to many patients.