Published on June 2, 2020
As states begin a phased approach to opening back up, you may have questions about COVID-19. Did you have it? What is the antibody test all about? We need reliable information about the accuracy of the COVID-19 antibody test, which looks for evidence of an immune response to infection.
Because of the way COVID-19 can hide in one’s system and not produce symptoms, it’s hard to know whether you have had it. One important factor is when the test is conducted in relation to when you may have been exposed to the virus.
“Antibodies in some persons can be detected within the first week of illness onset,” according to the U.S. Centers for Disease Control and Prevention (CDC).1 But, if you’re not experiencing symptoms, it’s harder to know when to get tested.
Antibody tests, using blood samples, are the current method to see if you’ve had the virus in the past. However, these tests can produce a false negative result if the test is conducted too soon, before antibodies have developed, according to the American Society for Microbiology.2
Specifically, the U.S. Food and Drug Administration (FDA) has called out the rapid test because of false negatives. In one study, the false negatives were about 15 percent, and others show a much higher rate.3
The FDA and other agencies are taking a very close look at these tests and working to improve them.
“This test can still be used and can correctly identify many positive cases in minutes. Negative results may need to be confirmed with a high-sensitivity authorized molecular test,” said Dr. Tim Stenzel, Director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health in an FDA news release.4
With more companies throwing their hats into the testing ring, the FDA, CDC and a branch of the National Institutes of Health (NIH) are working to make sure the blood tests are validated to detect the specific antibodies to the COVID-19 virus and not one of the many other viruses. COVID-19 is a novel coronavirus, but there are others out there.
“NIH’s National Cancer Institute has been checking out kits that are designed to detect antibodies to SARS-CoV-2 and have found mixed results,” Dr. Francis Collins of NIH wrote in a recent blog post. “In response, the FDA just issued its updated policy on antibody tests for COVID-19. This guidance sets forth precise standards for laboratories and commercial manufacturers that will help to speed the availability of high-quality antibody tests, which in turn will expand the capacity for rapid and widespread testing in the United States,” he wrote.5
The other side of the issue is the false positive rates. COVID-19 is one of many coronaviruses that the world has endured globally. The antibody test can yield a false positive if antibodies to coronaviruses other than COVID-19 are present, such as SARS-CoV (in 2003) and MERS-CoV (in 2012). So, test design is very important. What we are dealing with right now is SARS-CoV-2.
Johns Hopkins has been tracking the many tests that have been fast-tracked to test for the antibody. “A highly sensitive test should capture all true positive results. A highly specific test should rule out all true negative results,” they wrote.6
Sensitivity, in the clinical sense, is the test's ability to correctly identify people with antibodies (true positives) and specificity is the test's ability to identify those without the antibodies (true negatives), according to University of Washington Medicine.
Businesses, places of worship, civic organizations and summer camps are all eager to get back to a sense of normalcy. We all want to see our friends and go out for a meal, but the health experts urge caution while these tests are improved on.
The CDC said that the results also shouldn't be used "to make decisions about returning persons to the workplace.” So, working from home may continue until more evidence about these tests is available.
For patients with cancer and their loved ones, continue to do what you know works best. Staying safe at home may be the best option while research scientists work around the clock to get us more evidence-based guidance. Until then, be safe!
~Lauren Evoy Davis
Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.
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- Coronavirus Live Ask the Expert Webinars
- Cancer and COVID-19, When Will I Be Safe?
- Coping With Cancer and Coronavirus Anxiety
- Interim Guidelines for COVID-19 Antibody Testing. CDC
- Covid-19 FAQs. ASM.
- Study Raises Questions About False Negatives From Quick COVID-19 Test. NPR. April 21, 2020.
- Coronavirus (COVID-19) Update: FDA Informs Public About Possible Accuracy Concerns with Abbott ID NOW Point-of-Care Test. FDA. May 14, 2020.
- Collins, F. NIH Director’s Blog. May 7, 2020.
- Serology-based tests for COVID-19. Johns Hopkins University. May 26, 2020.