The viral load for hepatitis C refers to the amount of hepatitis C virus (HCV) present in a person’s bloodstream.

A hepatitis C viral load can indicate if people have contracted an active hepatitis C infection or whether treatment is reducing levels of the virus.

A high viral load indicates high virus levels, while a low viral load indicates lower amounts. The viral load levels do not relate to other effects of hepatitis C, such as liver condition.

In this article, we explore hepatitis C tests, what their results mean, and who requires testing.

Viral load refers to the amount of virus present in the bloodstream. Doctors use it as an indicator of whether a treatment is working to reduce virus levels. An undetected viral load suggests a successful treatment of hepatitis C. With treatment, doctors can cure over 90% of hepatitis C cases.

HCV causes hepatitis C, which is a liver infection. While hepatitis can be a temporary, mild condition, it may progress into a chronic condition. Without treatment, the infection can cause serious health problems, including damage to the liver.

Antibodies are proteins that travel through the blood as part of the immune system’s response to neutralize foreign substances or antigens in the body, such as viruses or bacteria. The body produces antibodies to fight specific antigens.

An HCV antibody test detects antibodies in the blood that the immune system has created to respond to an HCV infection.

Healthcare professionals use HCV antibody tests to determine if people may have had any previous exposure to HCV or if they have a current hepatitis C infection.

However, the test cannot tell the difference between previous exposure or current infection.

If results are negative or nonreactive, a person has not acquired the hepatitis C infection. However, if results are positive or reactive, it means an individual has had exposure to HCV at some point.

However, positive test results do not always mean an active virus — people who are clear or cured of the virus will still have antibodies in their blood.

If individuals test negative for HCV antibodies and have a low suspicion for any recent exposure to HCV, they will not need to take any further action.

Additionally, if people have a negative antibody test result but suspect they have had exposure to HCV, they can take a second test, called an HCV RNA test. This is important, as the body may not develop antibodies against HCV until 2 months after exposure to the virus.

If people test positive for HCV antibodies, they will also need to take an HCV RNA test.

Hep C virus RNA assays

An HCV RNA test shows whether people have an active hepatitis C infection or not. An HCV RNA test checks for the viral load to indicate the amount of the virus in the blood.

An HCV RNA test can also show how a person with a hepatitis C infection responds to treatment to see if medication is helping lower the viral load.

Viral load testing is important because it shows whether someone has an active hepatitis C infection or not. People can have antibodies in their blood from previous exposure to hepatitis C, but they may not have an active infection.

Viral load also shows the amount of the virus in the bloodstream. This can help indicate the effectiveness of treatments in reducing the virus by comparing viral load before, during, and after hepatitis C treatment.

However, the viral load does not indicate the condition of the liver — people will need liver function tests to assess any damage to the liver.

Low vs. high viral load

A low viral load means a person has low levels of HCV in their blood, while a high viral load indicates higher levels of the virus present.

According to the Department of Veterans Affairs, healthcare professionals usually define a low viral load as less than 800,000 international units per liter (IU/L). In contrast, a high viral load is more than 800,000 IU/L.

This measure can be in the millions — a result of more than 100,000,000 international units per milliliter (IU/mL) indicates an active HCV infection.

In contrast, a result of less than 15 IU/mL shows that HCV is present, but the level is not measurable. This may mean HCV is undetectable, or levels of HCV are too low to show on the test. People may require a follow-up test 1–2 months later to track any changes in these levels.

If a result is inconclusive, the test was not successful in measuring viral load, and people need to take another test.

If a result comes back as undetected, it means the test found no HCV is present.

The viral load can change depending on the treatment. If people have an increasing viral load, it may mean the treatment is not targeting the virus effectively. If they have a decreasing viral load, it may mean that the treatment is working.

Treatment for hepatitis C is highly effective for low and high viral loads. If individuals have an undetected viral load 12 weeks after completing treatment for hepatitis C, they no longer have the infection.

Healthcare professionals may test people with an HCV infection before, during, and after treatment to assess how effective treatments are in lowering the viral load. Testing is also crucial to determine if the therapy has cured hepatitis C.

People will need regular testing if they:

  • currently inject and share any needles, syringes, or other equipment for drug preparation
  • have any ongoing risk of contracting an HCV infection
  • have received or are receiving maintenance hemodialysis

The Centers for Disease Control and Prevention (CDC) recommend HCV testing in all adults over the age of 18 years at least once during their lifetime. Additionally, pregnant people should undergo testing for each pregnancy they have.

The CDC also recommends one-time testing for:

  • people with HIV
  • anyone who has ever injected drugs and shared needles, syringes, or any other equipment for drug preparation
  • people with consistently atypical alanine aminotransferase levels, which can indicate liver issues
  • individuals who have previously received a transfusion or organ transplant
  • any child from a biological mother with an HCV infection
  • healthcare workers who experience a needle-stick injury or exposure to HCV-positive blood

In addition, any person with concerns about acquiring HCV infection may speak to their doctor about taking an HCV test.

The hepatitis C viral load shows the amount of virus in a person’s bloodstream. This screening shows if an individual has an active HCV infection and whether they have a high or low viral load.

Viral load tests can indicate if hepatitis C treatment is effective, as the viral load will usually reduce if treatment is working. An undetected viral load means people no longer have HCV present in their bloodstream.