How to Find the Right COVID-19 Antibody Test
The Short Answer
COVID-19 antibody tests vary significantly in accuracy, with sensitivity and specificity rates that can dramatically affect how communities understand disease prevalence. The most reliable tests combine high sensitivity (ability to identify those exposed) with high specificity (ability to correctly identify those not exposed), and emerging research shows that tests detecting multiple antibody types may offer improved accuracy.
Understanding Antibody Testing Basics
When someone is infected with or exposed to a virus, the immune system produces proteins called antibodies that are specific to that pathogen. This same principle applies whether you’re dealing with COVID-19 or managing an autoimmune condition in which your immune system attacks your own tissues. These antibodies help the immune system recognize the virus in the future, enabling a faster, more effective response.
For communities trying to understand COVID-19 exposure rates, accurate antibody testing, also called serology testing, is critical. However, many tests lack the specificity and sensitivity needed to provide reliable results, leading to misinformation about disease prevalence.
Sensitivity vs. Specificity: Two Critical Measures
Two key factors determine the accuracy of antibody testing: sensitivity and specificity.
Sensitivity refers to a test’s ability to correctly identify those who have been infected or exposed. A test with 93% sensitivity means that out of 100 people actually exposed to the virus, it will accurately identify 93 of them. The remaining 7 will receive false negative results — testing negative despite actual exposure.
Specificity is the ability to correctly identify individuals who were never exposed. A test with 95% specificity means 95 out of 100 never-exposed people will test negative. However, 5 of those 100 will test positive despite having no actual exposure, a false positive result.
This matters because other types of coronaviruses can trigger false positives in COVID-19 antibody tests that lack high specificity. When these accuracy rates are extrapolated across millions of people, small percentage differences can lead to significant errors in understanding disease prevalence.
What Our Research Revealed About Test Accuracy
In our independent antibody study, we collaborated with medical directors from some of the nation’s top laboratories to identify the most accurate testing available. We found that many individuals who initially tested positive on antibody tests with lower specificity produced negative results when retested with more accurate assays.
Testing several antibody tests approved by the FDA’s Emergency Use Authorization, we discovered low false positives with many results through repeated testing and comparison with the Abbott Architect antibody test. When a test cannot reproduce the same result, it raises serious questions about reliability. These findings are especially common in areas where infection prevalence is below 5%.
The Abbott Architect Assay: Current Gold Standard
Among the antibody tests receiving FDA Emergency Use Authorization, the Abbott Architect Assay demonstrated one of the highest sensitivity and specificity rates available. According to a 2020 University of Washington study, the Abbott Architect assay showed:
- 95% sensitivity 14 days post-illness
- 100% sensitivity after 17 days
- 99.9% specificity (only 1 positive result among 1,020 frozen serum samples from 2019)
Emerging Testing Technology: Multi-Antibody Detection
Antibody testing continues to evolve as our understanding of COVID-19 improves. The Elecsys Test by Roche has emerged alongside the Abbott test as a highly accurate option, with a significant advantage: it detects multiple antibody types.
The immune system produces several antibodies in response to viral exposure, including IgG, IgM, and IgA. Most tests, including Abbott, focus on IgG antibodies , the most commonly used marker for past infection. The Elecsys Test detects all three types, potentially improving sensitivity by identifying more positive cases. This test received FDA Emergency Use Authorization with reported rates of 100% sensitivity and 99% specificity across multiple antibody types.
Best Practices for Accurate COVID-19 Antibody Testing
Recent CDC and FDA guidance recommends using two different testing methodologies when screening for COVID-19 antibodies to verify questionable results. In our testing, the Abbott Architect assay maintained accuracy with repeated testing.
As experts continue to develop more efficient and accurate testing methods each month, the field of antibody testing is becoming increasingly refined. When selecting an antibody test, ask your healthcare provider whether the test has FDA Emergency Use Authorization and what its published sensitivity and specificity rates are.
Frequently Asked Questions
What’s the difference between a false positive and a false negative on an antibody test?
A false positive occurs when someone who was never exposed to COVID-19 tests positive anyway. A false negative happens when someone who was actually exposed tests negative. Both types of errors skew our understanding of how widespread infection actually is in a population.
Why do some antibody tests detect IgG, IgM, and IgA while others only detect IgG?
Different antibody types appear at different stages after infection. IgM appears first (early response), followed by IgG (long-term immunity). IgA provides mucosal immunity. Tests that detect all three types may catch more positive cases, especially in people who are recently infected or in earlier stages of the immune response.
Can other coronaviruses cause a false positive on a COVID-19 antibody test?
Yes, especially on tests with lower specificity. This is why tests with 99%+ specificity are preferred; they’re less likely to cross-react with other coronavirus strains.
What specificity rate should I look for when choosing an antibody test?
Aim for 99% or higher specificity, particularly if you live in an area with low COVID-19 prevalence. This minimizes false positive results and ensures the test accurately distinguishes COVID-19 from other coronavirus infections.
Has testing accuracy improved since the beginning of the COVID-19 pandemic?
Significantly. As more clinical data became available and researchers refined testing protocols, both sensitivity and specificity rates improved considerably. Tests developed later in the pandemic generally show better accuracy than earlier versions.
Contact RedRiver Health and Wellness to work with a functional medicine doctor who can discuss accurate antibody testing and your immune health.
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