Older guidelines recommended hepatitis C virus (HCV) testing only for people thought to be at increased risk, but current guidelines say that all adults should be tested for HCV at least once. In addition, women should be tested during each pregnancy, and people with ongoing risk should be tested regularly. This includes people who inject drugs, people living with HIV and gay and bisexual men who take HIV pre-exposure prophylaxis (PrEP).

Hepatitis C testing is a two-part process. The first is screening for HCV antibodies, which shows whether a person has ever had the virus. The second is an HCV RNA, or viral load, test to see whether they have active infection and are eligible for treatment.

HCV antibody testing: Antibodies against HCV can be detected in the blood, usually within two or three months after the virus enters the body. A positive antibody test indicates that someone has been infected with HCV at some point. Around 25% of people who acquire HCV are able to naturally clear the virus without treatment, usually within six months. The rate of spontaneous clearance is lower for people living with HIV. A person with a recent acute infection may not yet have enough antibodies to test positive.

HCV RNA or viral load testing: If an antibody test is positive, the next step is to test for the actual virus to determine if a person still has active infection. Various methods are used to detect HCV RNA, including transcription-mediated amplification (TMR), polymerase chain reaction (PCR) and branched DNA (bDNA).

The presence of HCV RNA in the blood means the virus is actively replicating. People with a positive HCV RNA test may be eligible for antiviral treatment. During treatment, viral load tests may be done to see whether the medications are working. After treatment, they are used to verify that hepatitis C has been cured.

HCV genotype testing: Genotype refers to the specific type of virus. HCV has six major genotypes, with genotype 1 being most common in the United States.

In the era of interferon-based treatment and early direct-acting antiviral (DAA) therapy, genotype testing was an important part of hepatitis C care. Genotype 1—especially subtype 1b—is more difficult to treat. Early interferon-free DAA regimens worked against specific genotypes, so testing was important to guide treatment. But widely used modern DAAs are “pangenotypic,” meaning they work against all genotypes. People who will be treated with a pangenotypic regimen may not need genotype testing.

HCV viral load and genotype tests cannot determine whether or when someone with hepatitis C will develop cirrhosis or liver failure, so other tests are needed to monitor liver health.