Learn More about COVID-19 Antibodies

People who have been infected with SARS-CoV-2 (the coronavirus) and recover develop antibodies that fight off the infection. Antibodies are proteins in the blood that stick to the viral particles and help the body to clear the infection. Antibody tests are not used to diagnose a current infection, so these tests cannot be used early on when a patient is symptomatic to determine if they have the virus.  Antibody testing is used later to determine 1) if someone had COVID-19 in the past, and 2) the strength of their immune response. Research has shown that antibodies provide protection against re-infection, although strength of the protection and how long the protection may last may vary between patients. Different kinds of antibodies do different things. See below to learn more about IgG, IgM and Neutralizing Antibodies.

Most people who have been infected with SARS-CoV-2 produce antibodies rapidly and within 2 weeks of the first positive test or symptom onset nearly everyone will have detectable antibodies. There are two main kinds of antibody that can be detected in serum of COVID-19 patients: IgG and IgM. IgM is usually the first antibody produced by the immune system and IgG is usually produced second, although with COVID-19 scientists have found that this is not always the case.  Recovered patients may have only IgG or IgM, or both at the same time. Therefore, the best COVID-19 antibody testing strategy is to measure each of them separately.

The presence of either type of antibody means that you have been exposed to the virus and have some protection, but IgG persists for much longer and is responsible for long-term protection against re-infection. Unlike lower quality IgG tests that report a “+” or “-“, Granger Genetics’ IgG test is quantitative over 5 order of magnitude (from .6 to 1250 µg/mL), meaning that we are able to tell you how strong an immune response is, and monitor changes in patients’ antibody levels over time. When the IgG and IgM tests are used together with the Neutralizing Antibody test, patients and healthcare providers will have the most accurate measure of immune status.

Neutralizing antibodies are the most protective kind of antibodies against the SARS-CoV-2 coronavirus because they bind up the virus in the human body so that it cannot infect cells.  With other viruses, neutralizing antibodies are known to persist for years after infection and confer immunity to re-infection by the same virus.  Scientific research has shown that COVID-19 patients also develop neutralizing antibodies that are measurable for many months after infection, and there is evidence that the neutralizing antibodies against SARS-CoV-2 provide “true immunity”.  Granger Genetics’ own clinical research has shown that neutralizing antibodies can still be detected in the blood of patients who were infected in the earliest days of the pandemic.  Only time will tell how long they persist.

Neutralizing antibody testing is important, and it is most powerful when used together with IgG and IgM tests.  In fact, testing for Neutralizing Antibodies in addition to IgG and IgM has been used by scientists for decades to measure the strength of the immune response to vaccine candidates for viral infections such as Ebola, Influenza, and other infectious diseases. Today, companies developing vaccines for COVID-19 test for neutralizing antibodies together with IgG and IgM to prove to FDA that their vaccines give patients immunity from infection.  Any testing panel that does not include neutralizing antibodies is simply incomplete; when it comes to determining your immune status, three tests are better than one, and that is why Granger Genetics offers the Triple Test.

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