– Compared to antibodies of the IgM class, IgG antibodies have a relatively high affinity and persist in the circulation for a long time. The immunoglobulin G (IgG), on the other hand, is the most common antibody found in the blood and a major effector molecule of the humoral response that accounts for about 75 percent of serum antibodies in humans. IgM antibodies are the first line of immune defense against fighting pathogens. The IgM antibody is the largest antibody found in the blood and lymph fluid, and the first to appear to fight off a new infection. – IgG and IgM are two common types of antibodies found in the blood and they represent different stages of an immune response. Difference between IgG Test and IgM Test Antibodies So, IgG starts spiking as IgM starts coming down. It can also help to diagnose persistent infection. IgG antibodies are formed later than IgM antibodies and the test for IgG antibodies help determine the immunity status following a virus infection or active immunization. And the antibodies remain in the blood even after an infection has passed. These antibodies are produced 7 to 14 days after infection and they are detectable for weeks, months and even years. In comparison to IgM antibodies, IgG antibodies have a relatively high affinity and persist in the circulation for a really long time. The IgG antibodies express their predominant activity during a secondary antibody response. The IgG accounts for about 75 percent of serum antibodies in humans. The immunoglobulin G (IgG) is the most common antibody found in the blood and a major effector molecule of the humoral response. They are two common types of antibodies found in the blood. So, IgG and IgM represent different stages of an immune response. A serology test, however, does not detect the presence of the virus, but rather detect the antibodies that are produced by our body is fighting the virus. An antibody test (serology test) is therefore very useful in diagnosing an acute infection. For example, the antibody for SARS-CoV-2 is not the same as the antibody for any other virus, such as the chickenpox or HIV. They protect our body against antigens such as viruses, toxins or bacteria.Ī serology test can be used to detect the antibodies in our system because our body builds different antibodies to fight off different antigens. Also known as immunoglobulins, antibodies are produced by our immune system as part of an immune response. So, antibodies are nothing but large protein molecules that fight off against foreign objects that try to enter our body. The antibodies attack the virus and eliminate the virus from the system. When an individual is infected with a virus, like the SARS-Cov-2 which causes COVID-19, the person’s body starts to develop an immune response naturally by building antibodies to the virus.