This test is usually the first one used to detect infection with HIV. If antibodies to HIV are present (positive), the test is usually repeated to confirm the diagnosis. If ELISA is negative, other tests usually aren't needed. This test has a low chance of having a false result after the first few weeks that a person is infected. A hepatitis C antibody test is used to find out if you are infected with the hepatitis C virus (HCV). When your body is infected with a virus, it makes antibodies to fight the virus. The hepatitis C antibody test looks for antibodies that the body makes in response to the presence of HCV. HCV infects the liver, often causing inflammation and damage. It can lead to cirrhosis, liver failure, and liver cancer. It's more common in developing nations.