Covid-19 Tests: What’s the difference?


COVID-19. Just when many people were getting back to some semblance of normality, new variants and breakthrough infections have the world on edge, yet again. The Delta variant of COVID-19 is making waves throughout the world, prompting many to begin wearing a face mask and socially distancing. In addition to preventative safety measures, testing rates are rising in the United States. In fact, testing rates in late July were up more than 15% week-over-week, according to the Centers for Disease Control (CDC).


With testing and positivity rates up throughout the country, it’s important to know the differences in available tests in order to better inform testing decisions. Antigen lateral flow tests and PCR tests are the two most familiar types of COVID-19 testing currently available; however, they are not the only options on the table, particularly if you’ve already had a COVID-19 infection.


What is antibody testing for Covid-19?

Antibody testing also referred to as serology testing, is generally done after full recovery from a virus. A blood sample is tested to determine whether a patient has developed antibodies that are critical for fighting off and clearing out the virus from the immune system. If the test shows that a patient has antibodies, it is likely that they were infected with the virus at some point in the past. 


While in many cases, the presence of antibodies confers immunity against a particular viral infection, at this stage, it is unknown if COVID-19 antibodies confer immunity, and if so, for how long. The U.S Food and Drug Administration (FDA) has issued emergency use authorization (EUA) approval for a number of COVID-19 antibody tests during the pandemic, however, it can be difficult to understand the differences between antibody tests and neutralizing antibody tests. Below, we give more information about both types of antibody tests and why you should consider stocking both options at your medical facility. 


Rapid antibody tests detect if a person has an active, live virus in their system. Tests like AssureTech’s EcoTest COVID-19 IgG/IgM Rapid Test Device can determine whether a person’s immune system is currently fighting against COVID-19 infection. EcoTest is one of only a small number of COVID-19 rapid antibody tests that can detect two types of antibodies, IgM, which peaks early in the disease, and IgG which peaks later during the illness. This combination provides broader capture of patients exposed to COVID-19.


What are neutralizing antibodies for Covid-19?

Following infection, the body produces antibodies that bind to a specific part of a pathogen and decrease viral infection in cells. These antibodies, called neutralizing antibodies, help to protect a person from subsequent infection with the same virus. In the case of COVID-19, IgG neutralizing antibodies target the COVID-19 proteins and interfere with the virus’s ability to enter human cells if they appear in a person’s immune system again. Neutralizing antibodies are antibodies that are responsible for defending cells from pathogens – and can be used to detect if a person has an immune response triggered by both infection and vaccination.


A neutralizing antibody COVID-19 rapid test detects the IgG antibodies in human serum or plasma. Tests like the ImmunoPass COVID-19 Rapid Neutralizing Antibody test measures functional neutralizing antibodies within 10 minutes, unlike traditional tests which require days. The ImmunoPass Neutralizing Antibody test demonstrates the ability of antibodies to block the binding of COVID-19 viral proteins to the cells, providing immunity against infection and reinfection. Tests that detect neutralizing antibodies help give insight into levels of immune protection against COVID-19 infection, which can be helpful for those looking to return to their office or for children as the school year approaches. Additionally, neutralizing antibody tests can help to track vaccine efficiency, allowing scientists to study and understand the length of vaccine effectiveness and provide insight into the need for additional vaccine booster inoculations.


While it is important to test, track and monitor active COVID-19 infections in our communities, it is equally as important to test for antibody and neutralizing antibody presence in individuals who have been infected with the COVID-19 virus. As the United States faces another surge in COVID cases, consider stocking your medical office or lab with EcoTest and ImmunoPass for better COVID-19 antibody detection.