Hepatitis C is an infection caused by Hepatitis C virus, or HCV, a bloodborne virus that can cause both acute and chronic liver disease. HCV is an RNA virus with substantial genetic diversity, and its ability to persist in the body is strongly influenced by rapid viral variation and incomplete immune clearance. Acute infection is frequently asymptomatic, which means many people do not know they were infected. In a substantial proportion of cases, however, infection becomes chronic and can progressively damage the liver. Chronic HCV can lead to fibrosis, cirrhosis and hepatocellular carcinoma. WHO estimates that tens of millions of people live with chronic HCV infection worldwide.
Hepatitis C is primarily transmitted through exposure to infected blood. Historically, unsafe medical injections and unscreened blood transfusions were major transmission routes in many settings, while current transmission in many countries is strongly associated with sharing needles or other injecting equipment. Exposure can also occur through inadequately sterilised procedures, occupational needlestick injuries and certain sexual practices involving blood exposure. Sexual transmission is generally less efficient than bloodborne transmission but can occur. Preventive strategies therefore focus on safe healthcare procedures, screened blood supplies, sterile injecting equipment and harm-reduction measures. Unlike Hepatitis A, HCV is not primarily spread through contaminated food or water.
The natural history of Hepatitis C has two major phases: acute infection and chronic infection. Acute HCV infection is often clinically silent, but some people develop nonspecific symptoms such as fatigue, nausea, abdominal discomfort, dark urine or jaundice. Approximately 15 to 45 percent of infected people can spontaneously clear the virus within six months, whereas the remainder develop chronic infection. Chronic HCV can remain asymptomatic for many years, allowing fibrosis to progress unnoticed. WHO estimates that among people with chronic infection, approximately 15 to 30 percent may develop cirrhosis within 20 years, although individual risk varies according to host and disease factors.
Diagnosis of Hepatitis C uses a two-stage approach. Initial testing commonly detects antibodies against HCV, establishing that a person has been exposed to the virus at some point. A positive antibody result does not by itself prove that active infection remains because antibodies can persist after spontaneous clearance or successful treatment. Detection of HCV RNA through nucleic-acid testing establishes current viral infection and guides treatment. This distinction is fundamental: antibody positivity and active infection are not synonymous. Additional assessment evaluates liver injury and fibrosis and may include blood tests, non-invasive fibrosis measurements and imaging. Early diagnosis is particularly important because chronic HCV can remain clinically silent until advanced liver disease develops.
Hepatitis C has been transformed by the development of direct-acting antiviral medicines. Modern treatment regimens target specific viral proteins required for replication and can cure more than 95 percent of appropriately treated people. Treatment is generally shorter and more effective than the interferon-based therapies that dominated earlier eras. Successful treatment eliminates detectable HCV infection but does not create protective immunity, so a person can become reinfected after cure if exposed again. Treatment can reduce future liver-related complications, particularly when administered before advanced fibrosis or cirrhosis develops, although people with established cirrhosis may require continued liver monitoring even after viral eradication.
There is currently no effective vaccine against Hepatitis C. Prevention therefore depends on preventing blood exposure and diagnosing infection early. Blood donation screening, sterile medical equipment, safe injection practices and harm-reduction services such as needle and syringe programmes reduce transmission. Testing people with relevant exposure risks is important because symptoms are often absent. Unlike Hepatitis B, vaccination cannot provide a preventive alternative, and unlike Hepatitis A, improved sanitation does not directly prevent the main transmission pathway. These differences illustrate why hepatitis prevention must be tailored to the biology and epidemiology of each virus rather than applying one universal strategy.
Hepatitis C should be distinguished from Hepatitis B even though both can cause chronic infection, cirrhosis and liver cancer. HBV has an effective vaccine and can be efficiently transmitted from mother to child at birth and through sexual exposure, whereas HCV is predominantly bloodborne and has no vaccine. HCV also differs from Hepatitis A because it can persist chronically, whereas HAV normally resolves without chronic infection. Another important distinction is between curing HCV and acquiring immunity: successful antiviral treatment clears the virus but does not reliably protect against future infection. A positive HCV antibody test after treatment therefore does not necessarily mean treatment failure or persistent infection.
The historical development of Hepatitis C is closely linked to improvements in blood screening, molecular diagnostics and antiviral pharmacology. HCV was identified after years in which many cases of post-transfusion hepatitis could not be assigned to the previously recognised hepatitis viruses. Molecular testing subsequently enabled direct identification of active infection, while direct-acting antivirals transformed treatment from prolonged, difficult-to-tolerate regimens into highly effective curative therapy.
Despite this therapeutic advance, the public-health challenge remains substantial because many infections are undiagnosed and access to testing and treatment is uneven. WHO estimates that HCV caused hundreds of thousands of deaths in 2024, predominantly through cirrhosis and hepatocellular carcinoma, demonstrating why diagnosis and treatment remain important even though the infection is now usually curable.
