COVID-19 Anti-Body Testing: What It Tells You What It Won't

Antibody testing may make us better prepared for a second wave of COVID-19
By James W. Lederer, Jr., M.D. and Jessica Krochmal, M.D.

As we face the very real possibility of a resurgence of COVID-19 this fall and winter, antibody testing may help us better understand just how widespread the virus truly was in this first phase and be better prepared to contain a second wave.

The importance of antibody testing in the long-run is that it gives us a much clearer fix on what percentage of the population actually has had COVID-19 so far, with the likelihood that many people who contracted the virus didn’t develop serious symptoms or any symptoms at all.

In a recent round of antibody testing in Berkshire County, out of 2,500 people tested, nearly 230 or nine percent tested positive for having had the virus in the past, even if they had no symptoms. When you compare that to the 4.1 percent or 537 out of 13,000 people who previously tested positive for COVID-19 in diagnostic swab tests, it becomes evident that more than twice the number of people had the virus here than the earlier diagnostic numbers revealed. 

The reason antibody tests become important is that they paint a clearer picture of how far the virus has spread through a population. That knowledge can help us take measures to suppress a resurgence. It can help in contact tracing to assess who else might be at risk of infection.

While antibody testing for COVID-19 will help you know if you had the disease in the past, even if you had no symptoms, it doesn’t guarantee you will be immune from the virus in the future or how long that immunity might last. At this early stage of antibody testing nationwide, the test simply won’t answer those questions.

Antibody blood tests should not be confused with the viral diagnostic tests done with nasal swabs. Antibody tests look for past infections. They are not used to diagnose a current COVID-19 infection because it can take one to three weeks after infection for your body to make antibodies. To see if you are currently infected, you need a viral test. Viral tests identify the virus in samples from your respiratory system, such as a swab from the inside of your nose.

The antibody test itself is a simple blood draw with a fairly fast turnaround.  The test looks for antibodies, which are proteins in the blood which help fight off infections and can provide protection against getting that disease again. But again the caveat: there’s no guarantee. 

Because a positive test for COVID-19 antibodies does not mean a patient is immune going forward, people should continue to follow all of the precautions put in place to help prevent the spread of the virus, including social distancing and facial masking. Antibody tests should not be used to guide decisions on whether to stop isolation or return to work. Assume you are still vulnerable to infection and can still infect others without knowing it.

So the question becomes: should you get an antibody test for COVID-19?

The answer, at this time, is that most people do not need to have an antibody test. But if your doctor feels you should have one to get a clearer health profile – or if you want to be tested for your own peace of mind – then you should consider it. Expect to be responsible for any co-pays, deductibles or self-pay required by your health insurer.

To collect the data that can give public health officials a more accurate picture of how far the COVID-19 virus has spread – and be better prepared for a second wave this fall and winter – hospitals nationwide are routinely doing antibody testing of inpatients and accepting referrals from doctors for outpatient testing. 

James W. Lederer, Jr., M.D, is the Chief Medical Officer and Chief Quality Officer of Berkshire Health Systems. Jessica Krochmal, M.D., is Chief of Pathology and Clinical Laboratories at Berkshire Medical Center.