Are you among the many patients who have considered taking a COVID-19 antibody test in order to determine whether or not you are protected from the virus?
Maybe you are vaccinated and want to know whether your protection has weakened to the point that you should get a booster shot, or perhaps you have recovered from COVID-19 and want to measure the strength of the immune response generated by the infection. Conversely, you might finally be planning an overseas vacation now that many countries have opened their doors to visitors and want to know how safe you will be while travelling abroad.
Regardless of your reason, should you schedule an antibody test in order to make an informed decision? Not so fast.
The antibody threshold that effectively prevents infection from COVID-19 is unknown. While there is a connection between higher antibody levels, specifically those known as neutralizing antibodies that prevent the virus from entering other cells and increased protection against COVID-19, the antibody level that a person needs to be protected from infection or severe disease is still being researched.
Another limitation of antibody testing is that it does not account for the activity of B-cells or T-cells, the immune cells that produce antibodies as well as those that identify and kill other cells that have become infected. Therefore, these tests are merely a snapshot of one branch of the immune system rather than a complete picture of an individual’s immune response to COVID-19.
On the other hand, antibody testing can determine past exposure to the virus. It is particularly useful for immunocompromised individuals, or patients who are using immune suppressant medication for autoimmune disease or organ transplant. If these patients are tested approximately one month after vaccination, an antibody test can reveal what type of response the vaccine produced thus these patients could be more cautious in their activities, if necessary.
While antibody testing may seem like a logical precaution, ultimately, the metrics provided should not be used to determine whether or not a non-immunocompromised patient remains safe from contracting or transmitting the virus.
Terry Pfau DO, HMD