COVID-19 Antibody Assay

Our COVID-19 assays are laboratory developed tests (LDT) to determine the presence of IgM and IgG antibodies in patients who have been exposed to COVID-19. These assays have been validated and are performed in a CLIA certified high complexity laboratory.

The test offers a way for a person to know if they have developed antibodies that are crucial to fighting COVID-19. This test is not for individuals who are currently showing active symptoms of COVID-19. Those showing symptoms should contact their physicians regarding molecular diagnostic testing for virus detection.

IgG & IgM Antibody Test

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 monitor changes in patients’ antibody levels over time. When the IgG and IgM tests are used together with the Neutralizing Antibody test, you and your healthcare provider will have the most accurate measure of your immune status.

In most patients, IgG antibodies develop 7-10 days after symptoms of COVID-19 begin. The results of this test may indicate that a person has had COVID-19 in the recent past and has developed antibodies that may offer protection from future infection.

IgM is the first antibody produced by the immune system. A positive IgM test indicates that a person has been infected and has begun to mount/have an immune response to the virus. IgM antibodies disappear soon after the virus has been cleared from the body. A person with a positive IgM test may still have an active infection and should self-isolate.

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Antibodies can provide protection against re-infection, although strength of the protection and how long the protection may last vary by disease. People with antibodies may have a level of protection against SARS-CoV-2 re-infection, although researchers are still determining the level of protection.

Test was FDA Allowed on May 2, 2020. (EUA application #201535 currently under review)
(NOTE: There is a difference between Allowance and Approval. Test kit manufacturers must apply for FDA Approval. Granger Genetics is not a test kit manufacturer. Laboratories like Granger Genetics who are CLIA-accredited to perform complex testing do not apply for FDA approval of their tests. However, labs may voluntarily submit formal “Notice” to the FDA containing all their test validation data, and after the FDA accepts the Notice, the test is referred to as “Allowed”. Granger Genetics’ COVID-19 Antibody Tests are FDA Allowed.)

*Results from antibody testing should not be used as the sole basis to diagnose or exclude SARS-CoV-2 infection or to inform infection status.
*Positive results may be due to past or present infection with non-SARS-CoV-2 coronavirus strains, such as coronavirus HKU1, NL63, OC43, or 229E.

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Neutralizing Antibody Test

Granger Genetics is proud to announce that we will be the first laboratory in the US to offer the cPASS™ Surrogate Viral Neutralization Test. 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, thus providing true immunity.

Testing for neutralizing antibodies in addition to IgG and IgM is important because not all IgG and IgM against SARS-CoV-2 is effective at neutralizing virus; in other words, just because you have antibodies doesn’t mean that you have true immunity. Just knowing that you have antibodies to the novel coronavirus isn’t enough; Granger Genetics’ neutralizing antibody test tells you how well those antibodies work.

The gold standard test for detection of neutralizing antibodies uses live virus and cells, making it dangerous, expensive, slow, and not practical for routine diagnostic use. The cPASS™ test is a “surrogate” laboratory test, meaning that it does not require live virus; cPASS™ is just as accurate as the live virus tests at detecting neutralizing antibodies, but it is rapid and inexpensive.

Granger Genetics collaborated closely with the test manufacturer (GenScript, Piscataway, NJ) during the clinical validation of the cPASS™. The cPASS™ diagnostic test has already received its CE-IVD approval in Europe and HSA approval in Singapore. FDA approval is expected within weeks (EUA application #200661). Learn more about the cPASS™ Neutralizing Antibody test by clicking on the links below.

https://apnews.com/b4c1ca7c9f1841a09d59efaca5b85c95

https://www.prnewswire.com/news-releases/genscript-files-for-emergency-use-authorization-of-rapid-sars-cov-2-neutralization-antibody-detection-kit-301069883.html

https://www.bioworld.com/articles/435546-genscript-seeks-eua-for-test-that-indicates-immunity-to-covid-19

https://www.genscript.com/cpass-sars-cov-2-neutralization-antibody-detection-Kit.html

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Neutralizing Antibody Panel Test

The Neutralizing Antibody Panel is the full COVID-19 Panel including both the Neutralizing Antibody Test and the IgG & IgM Antibody Test

David G. Bostwick MD, Rebecca Caffrey PhD, and Nicole Waltrip MS

Why is antibody testing considered necessary by public health officials? Such testing can’t even tell you if you are currently infected and shedding virus; however, it can determine if you were infected. Concerns have been raised about inaccurate testing and false results. On May 4, the FDA weighed in, stating, “…we unfortunately see unscrupulous actors marketing fraudulent test kits and using the pandemic as an opportunity to take advantage of Americans’ anxiety.” In response, the agency strengthened testing to require overall sensitivity of 90% and specificity of 95%. This action will likely improve testing accuracy quickly.


There is good news for those who want to know if they were infected, including sick patients who were not able to get tested, those who suspect their swab test was a false negative, and those who were exposed to COVID-19. A recent study from China reported that antibody testing provided definitive evidence of prior infection. Investigators found that all 285 infected patients under study developed antibodies within three weeks of onset of symptoms, suggesting that the immune system of survivors invariably develops a response specific for COVID-19.

Communities benefit from antibody testing by determining the extent of asymptomatic and symptomatic infection, tracking of infections geographically and over time, estimating the prevalence of infection in the population, and identification of recovered patients with antibody titers high enough to donate convalescent plasma to treat the sickest patients currently suffering from infection.

Those with antibodies can serve as donors to help save lives of infected critically-ill patients. Infusion of antibody-rich convalescent blood serum into sick patients has been successfully used for more than 130 years in numerous outbreaks, including diphtheria, 1918 Spanish flu, measles, chickenpox, SARS, and even Ebola. Such treatment exploits pathogen-specific protective immunity conferred by antibodies, and multiple recent studies have demonstrated significant clinical improvement and decreased mortality in seriously ill patients within a few days.

Yet, we still need confirmation that antibody-mediated virus-specific immunity can protect against re-infection, and we need to know how long it will last. The duration of immune protection is known for most other viruses. For example, antibodies to measles last a lifetime, whereas patients infected with another coronavirus—SARS—lose all antibodies by six years. At present, we can only surmise that the development of antibodies in COVID-19 infection confers some level of immunity.

The only real solution for reopening our world and returning to normalcy is to develop herd (community)immunity, and this can only be measured by antibody testing. The concept of herd immunity is grounded in scientific studies that the greater the number of people who are immune to a given pathogen, the fewer that can be infected. Recent surveys show wide variability in antibody prevalence, ranging from about 4 percent in Los Angeles, 25 percent in New York City, and 31.5 percent outside Boston. All are far short of the estimated 60-85 percent needed for COVID-19 infection herd immunity.

As we strive to reach herd immunity, whether though widespread recovery from infection or future vaccination, antibody testing will play a vital role. All agree that we will recover from a pandemic that spawned the largest and only healthy-person quarantine in history by taking the only medicine that is currently available to all of us: “a tincture of time.”

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How to get testing done

We will be offering onsite testing available at certain times or you can reach out to your healthcare provider in order to be tested. Please click here to see more information about onsite testing

Testing for Businesses

We are committed to helping businesses keep their employees safe. If you are interested in getting your employees tested please click here.

COVID-19 Sample Submission Form      Frequently Asked Questions

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