Hepatitis is an inflammation of the liver that is caused by a variety of infectious viruses and non-infectious agents leading to a range of health problems, including severe liver damage and cancer, some of which can be fatal. There are 5 main strains of the hepatitis virus, referred to as types A, B, C, D and E. While they can all cause liver disease, they differ in important ways including modes of transmission, severity of the illness, geographical distribution and prevention methods.

In particular, types B and C lead to chronic disease in hundreds of millions of people and together are the most common cause of liver cirrhosis, liver cancer and viral hepatitis-related deaths. They are among the main infectious disease killers, causing an estimated 1.3 million deaths per year. An estimated 304 million people worldwide live with hepatitis B or C, and for most, testing and treatment remain beyond reach.

WHO’s Global Health Sector Strategy on HIV, Viral Hepatitis and Sexually Transmitted Infections (2022–2030)   outlines clear targets to eliminate viral hepatitis as a public health problem. The strategy aims to reduce new hepatitis infections to 520 000 cases annually and hepatitis-related deaths to 450 000 by 2030, which represents a 90% reduction in incidence and a 65% reduction in mortality compared to 2015. Without urgent and sustained action, however, viral hepatitis is projected to cause an additional 9.5 million new infections, 2.1 million liver cancer cases, and 2.8 million deaths by 2030. These outcomes are largely preventable through the scale-up of hepatitis B vaccination, improved access to prevention, testing and treatment for hepatitis B and C, and targeted public education campaigns to raise awareness and reduce transmission

Many people with hepatitis A, B, C, D or E exhibit only mild symptoms or no symptoms at all. Each form of the virus, however, can cause more severe symptoms; notable is hepatitis E infection in pregnant women. Symptoms of viral hepatitis may include fever, malaise, loss of appetite, diarrhoea, nausea, abdominal discomfort, dark-coloured urine and jaundice (a yellowing of the skin and whites of the eyes). Hepatitis B, C and D virus can also cause a chronic liver infection that can later develop into cirrhosis (a scarring of the liver) or liver cancer. These patients are at risk of premature death.

Hepatitis D (HDV) is only found in people already infected with hepatitis B (HBV); however, the dual infection of HBV and HDV can cause a more serious infection and accelerated progression to cirrhosis and cancer. HBV, HCV and HDV cause hepatocellular carcinoma and are considered carcinogenic.

Safe and effective vaccines are available to prevent hepatitis B virus (HBV) infection, and when given at birth, as part of the childhood vaccination series, strongly reduces the risk of transmission from mother to child. Hepatitis B vaccination also protects against hepatitis D virus (HDV) infection. Chronic HBV infection can be treated with antiviral agents. Treatment can slow the progression of cirrhosis, reduce incidence of liver cancer and improve long term survival. Only a proportion of people with chronic HBV infection will require treatment. A vaccine also exists to prevent infections of hepatitis A (HAV) and E (HEV). It is advised to avoid unnecessary medications due to the negative effect on liver function caused by these infections.

Hepatitis C (HCV) can cause both acute and chronic infection. Chronic HCV infection can lead to long-term complications, including cirrhosis or cancer. There is no vaccine for HCV. Antiviral medicines can cure more than 95% of persons with HCV infection, thereby reducing the risk of death from cirrhosis and liver cancer, but access to diagnosis and treatment remains globally low.

HAV and HEV are most common in low- and middle-income countries due to reduced access to clean and safe water sources and the increased risk of contaminated food. A safe and effective vaccine is available to prevent HAV and HEV infections. Most HAV and HEV infections are mild, with the majority of people recovering fully and developing immunity to further infection. However, these infections can also be severe and life threatening due to the risk of liver failure.