How hepatitis C testing works: Diagnostic tests

Key points

All hepatitis C tests used in Canada require a blood sample.
The availability of different testing methods varies across provinces and territories.
Two tests are usually required to confirm a current hepatitis C infection: an antibody test and an RNA test.
A hepatitis C antibody test detects antibodies in the blood to determine if a person has ever had a hepatitis C infection.
A hepatitis C RNA test detects the genetic material of the virus to determine if a person has a current hepatitis C infection.
In some cases, it is recommended that a person have only an RNA test. This happens most often when a person is being tested for hepatitis C reinfection.

The hepatitis C testing process

Two test results are usually required to determine if someone currently has hepatitis C. All hepatitis C tests in Canada use a blood sample. Often the two tests can be done at the same time with the same blood sample, but sometimes two separate blood draws will be required for the two tests to be completed.

Hepatitis C antibody test

The first test is a hepatitis C antibody test. This test detects antibodies in the blood to determine if a person has ever had a hepatitis C infection.

A non-reactive (negative) antibody test result indicates that the person does not have hepatitis C antibodies and has never had a hepatitis C infection. No further testing is required.
A reactive (positive) antibody test result indicates that the person has antibodies to hepatitis C and therefore has had a hepatitis C infection at some point in their life.

The antibody test alone cannot tell whether the person has a current hepatitis C infection. A person will test positive for hepatitis C antibodies if they have a current hepatitis C infection, but also if they have had a hepatitis C infection in the past. In other words, people will have hepatitis C antibodies for life, even if they spontaneously cleared the virus in the past or if they were treated and cured. Once a person receives a positive antibody test result, there is no need for them to get tested ever again for hepatitis C antibodies.

Hepatitis C RNA test

The second test is a ribonucleic acid (RNA) test, which detects the genetic material of the hepatitis C virus to determine if a person has a current hepatitis C infection.

A non-reactive (negative) RNA test result indicates the person does not have a current hepatitis C infection.
A reactive (positive) RNA test result indicates the person has a current hepatitis C infection.

Some jurisdictions may occasionally use a core antigen test to confirm a current infection. This test detects proteins that are part of the hepatitis C virus.

Reinfection

There is no immunity against hepatitis C. If a person is cured of or has cleared hepatitis C, they can still get it again. This is called reinfection.

If there is a chance that a person might have become reinfected, it is recommended that they have only an RNA test. This is because for someone with a reinfection, it is already known that the antibody test result will be positive.

Types of tests used

All hepatitis C tests used in Canada require a blood sample. The following tests are currently used in Canada, although availability will vary across provinces and territories. All of these tests are very accurate at identifying markers of hepatitis C infection (e.g., antibodies or parts of the virus) in the blood.

Standard hepatitis C testing

For standard hepatitis C tests, a blood sample is drawn from a person’s vein and sent to a public health laboratory for hepatitis C testing. Most jurisdictions in Canada have implemented reflex testing, which means that both the antibody and RNA tests can be conducted with one blood sample. However, reflex testing is guided by specific laboratory algorithms and previous test history, meaning that repeat testing does not always follow the same process, and a healthcare provider may need to order the RNA test specifically to ensure that it is completed.

In jurisdictions without reflex testing, a person is required to provide one blood sample for the antibody test and, if the test result is reactive, return to provide a second blood sample for the RNA test.

Dried blood spot (DBS) testing

In dried blood spot (DBS) testing, a blood sample is collected from a finger prick, dried on a paper card and sent to a laboratory for analysis. DBS testing can be used for both antibody and RNA testing. DBS testing also offers other advantages: it may help to expand access to testing in rural and remote communities, it can be an alternative to drawing blood from a vein, and the same card can be used to test for other infections. However, DBS testing is only available in some locations in Canada.

Point-of-care (POC) testing

A hepatitis C point-of-care (POC) test uses a blood sample taken from a finger prick for immediate testing onsite. Point-of-care tests approved for use in Canada can detect either hepatitis C antibodies or RNA. The time required to obtain a result varies depending on the test; for antibody testing, it can be as little as one minute or up to 20 minutes, whereas RNA point-of-care testing takes 60 minutes for a result. Point-of-care testing is only available in some locations in Canada.

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