COVID-19 Antibody Testing

As you all are aware, COVID-19 is the current pandemic wreaking havoc globally. Schools have been shut down, people have had to stay home from work, and only “essential” jobs are able to continue at this time. All of these precautions have occurred to not only stop the spread of COVID-19, but also to help relieve the healthcare workers from an onslaught of patients. Currently, the healthcare professionals are increasing their testing for the coronavirus, and there are two types of tests available. One is called the NAAT (nucleic acid amplification test) and it tests for the virus’s RNA genome¹. The other test is a serology test, and it finds antibodies present in the blood to see if the patient’s body is fighting off COVID-19. Specific antibodies allow experts to determine if the body is fighting off the virus or not².

From the serology test, a titer is gathered. This titer determines how much of an antibody is present in the blood. According to the Asian Pacific Journal of Allergy and Immunology, the antibody IgM peaks around day 9 of the coronavirus infection and IgG increases during the second week of the viral infection. Therefore, depending on the IgM and IgG titers, researchers can determine if the patient is in the process of fighting off coronavirus, if the patient has recovered from coronavirus, or if the patient has not had coronavirus.

If a patient tests positive for only an IgM titer, this means that the patient has come into contact with the coronavirus, because IgM is the first antibody released to fight off an infection. This also means that the patient is in the early stages of infection, because IgG has not been found in the blood yet. If a patient tests positive for both IgM and IgG, this means that the patient is in the middle stages of infection and that they are beginning to make memory cells that will be better equipped to fight off this infection if they face it in the future. If the patient is only IgG positive, then the patient has already fought off the active infection of COVID-19, is in the last stages of infection or is immune to COVID-19. Lastly, if a patient tests negative for both IgM and IgG, then the healthcare professional can determine that the patient has not been exposed to coronavirus.

I hope that the researchers can improve their NAAT and serology testing so that everyone can more efficiently be tested for coronavirus, and I hope in rural towns like my own, that testing becomes more prevalent and available for the population. In addition, I think it is important that people understand how these tests work and what the test results mean, as understanding every aspect of the coronavirus and its treatment will help ease the minds of the global population and help us all work together in protecting ourselves against COVID-19.

References:

1. Center for Devices and Radiological Health. “FAQs on Diagnostic Testing for SARS-CoV-2.” U.S. Food and Drug Administration. FDA. Accessed April 12, 2020. https://www.fda.gov/medical-devices/emergency-situations-medical-devices/faqs-diagnostic-testing-sars-cov-2.
2. “Global Progress on COVID-19 Serology-Based Testing.” Johns Hopkins Center for Health Security, April 10, 2020. http://www.centerforhealthsecurity.org/resources/COVID-19/serology/Serology-based-tests-for-COVID-19.html.