Coronavirus Antibody Testing

What does a positive result mean and how can we help to flatten the curve?


Kaitlyn Romanger

As COVID-19 makes its way through the United States, a large variety of antibody tests are becoming available to the public.

When the Coronavirus pandemic reached the United States at large in early 2020, there was low quality and scarce testing for the virus. Now, nearly two months since social distancing measures were put into place, more and more people are being tested for coronavirus antibodies, and some test positive. 

According to the Center for Disease Control (CDC), as of May 22, 2020, over 13 million coronavirus tests have been administered to the public. Many of these tests are viral tests, of which a positive result indicates the presence of SARS-NCoV-2 in one’s system, the virus linked to the development of COVID-19. A second test, called a COVID-19 antibody test, detects the presence of antibodies or convalescent plasma in one’s system. Unlike a positive result on the viral test, testing positive for antibodies does not mean that one has the virus. Rather, it indicates that one has previously been exposed to the virus. This could mean that a person who tests positive on the antibody test had COVID-19 at some point in the past year, even if they were asymptomatic. 

Although the presence of convalescent plasma in one’s blood tells doctors that a person has the tools necessary to fight off the virus, the United States Food and Drug Administration (FDA) has found that many tests yield false negatives. “I’m not sure about how reliable these tests are,” said Farhan Tanvir ’21. “ However, I think that a positive result is more likely to be correct than a negative result because of the possibility of a false negative.” Tanvir expresses that with any widespread testing, variability and outliers are sure to follow. Along with the inevitability of inconsistencies, however, is the fact that the demand for testing in the United States has prompted labs to administer tests that have not been FDA approved, many of which are largely unreliable.  

Under the revised May 16, 2020 policy issued by the FDA, in order for a lab to commence testing, their tests must be approved under the Clinical Laboratory Improvement Amendments (CLIA) by the Centers for Medicare and Medicaid Services (CMS). The lab also must submit their tests for Emergency Use Authorization (EUA) approval by the FDA. As of May 23, 2020, only 12 antibody tests have been EUA approved, with over 200 still waiting for approval. 

We unfortunately see unscrupulous actors marketing fraudulent test kits and using the pandemic as an opportunity to take advantage of Americans’ anxiety,” wrote Anand Shah and Jeff Shuren in an FDA announcement on May 4, 2020. Deputy commissioner for Medical and Scientific Affairs and director of the Center for Devices and Radiological Health, respectively, Shah and Shuren insist that the FDA is doing the most it can to make testing more available to the public, while upholding the standard of reliability that makes the tests effective determinants of the presence of convalescent plasma. They also acknowledge, however, that testing isn’t a perfect science. 

Mr. Daniel McNickle, AP Biology and Psychology teacher at Bronx Science, couldn’t agree more. “Antibodies are proteins produced by our immune systems that have the property of being able to bind specifically to another molecule, most often another protein. Antibody binding is one of the ways our immune system detects and kills specific disease-causing organisms,” said Mr. McNickle. He went on to explain how more than one antibody can bind to the same protein, a process that aids in the contraction of many diseases, including Coronavirus. 

“Antibody testing involves looking for those antibodies that could be used to attach to the SARS-NCoV-2 virus that causes COVID-19,” said Mr. McNickle. “There are a lot of possibilities, so any one test is likely to miss the uncommon ones. This produces false negatives, and, because there are other coronaviruses out there, exposure to one of them might lead your body to make antibodies that also, coincidentally, stick to SARS-NCoV-2. This leads to false positives.”

Although false negatives and positives are possible, according to the FDA, a positive result on an antibody test may qualify one to donate blood to COVID-19 patients. The FDA specifies that the American Red Cross is accepting blood donations from people who have recovered from COVID-19 for at least two weeks, are generally healthy, are at least 17 years of age, and weigh at least 110 pounds. 

The hope of the Red Cross is that by introducing coronavirus antibodies to a patient’s system, that patient will not only be able to use those antibodies to fight off the virus, but that their cells will be able to produce their own antibodies, using those from the donated plasma as models. 

Both the FDA and the Red Cross also encourage those who haven’t had COVID-19 to donate blood, as the emergence of the virus in the United States has caused an imbalance in blood reserves available to patients. 

Assuming I am tested positive for antibodies, I would donate,” said Annie Wang ’20. “With the development of COVID-19 over the past few months, and with new research showing how antibody testing can be used to help treat those that have been diagnosed [with COVID-19], I would definitely invest some time to donating blood with the hopes of it being a beneficial factor for the recovery of those suffering from the virus.” 

As testing availability increases across the country, it’s important to know which tests are reliable and what the results mean. However, getting tested is only one piece of the puzzle. Our doctors and specialists are fighting to learn all that they can about COVID-19 to develop a vaccine. Contribute to the fight by following social distancing measures, reviewing the conclusions of the FDA and the CDC regarding antibody testing, and donating blood to the Red Cross. Although the pandemic and its effects will be around for some time to come, we can help to flatten the curve before more lives are lost. 

“Antibody testing involves looking for those antibodies that could be used to attach to the SARS-NCoV-2 virus that causes COVID-19,” said Mr. McNickle. “There are a lot of possibilities, so any one test is likely to miss the uncommon ones.”