ABOUT THE NEUTRALIZING ANTIBODY TEST

Q: Why is this test important?

A: It has been clearly shown and acknowledged that vaccine efficacy (immune protection) wanes over time. The level of immune protection can also vary between individuals based on pre-existing conditions and on the type of vaccine (manufacturer) given. NAbs are generated by your immune cells in response to a vaccine or to exposure. This test defines a quantitative (percentage) of Nabs present. The FDA EUA test measuring Nabs defined  > 30% as Positive protection against the SARS-CoV-2 virus.  Understanding your immune status and level of protection is critical in the decision-making regarding vaccine boosters, getting a vaccine and understanding protection against different variants. It is important to understand that immune protection is not immunity. This is issue has also clearly been defined by the FDA recently – “Immunization: A process by which a person becomes protected against a disease through vaccination.”   Any decision making related to  the results of this  test should be made in consultation with your physician or health care provider.

Q: What is the difference between an Antibody Test and a Neutralizing Antibody test?

A: A common misconception is that antibody tests which are commonly available provide the same information. This is incorrect. Standard antibody tests measure all antibodies, binding and neutralizing. This will give you an idea that you have been exposed to the virus but not the level of your immune protection. This is only defined by the neutralizing antibody test.

Q: What is an FDA EUA test?

A: The Emergency Use Authorization Authority allows the FDA to streamline the approval process for laboratory tests which are deemed as essential countermeasures against public health threats such as the COVID-19 pandemic.

Here a a few links from the FDA site that will explain this process:

1. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-first-test-detects-neutralizing-antibodies-recent-or#:~:text=Today%2C%20the%20US%20Food,viral%20infection%20of%20cells.
2. https://www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/emergency-use-authorization

Q: What is a Laboratory Developed Test?

A: A Laboratory developed test or LDT are laboratory tests that that are unique or modifications of existing tests. These LDTs  are developed by  laboratories which have the technical expertise and follow regulatory standards and protocols (CLIA).

Here is a link on the FDA website defining these tests. As noted on the site “LDT’s are important to the continued development of personalized medicine, so it is important that in vitro diagnostics are accurate so that patients and health care providers do not seek unnecessary treatments, delay needed treatments, or become exposed to inappropriate therapies.”  An example of an LDT in the Comprehensive Immunity Test is the percentage of protection of  against the Omicron variant.