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So You Got Your Antibody Test Results Back. Now What?
What to make of a positive, negative, or equivocal result
The accuracy of antibody tests is still highly debatable, but they’re quickly becoming available in the U.S. These tests look for Covid-19 antibodies in the blood, which the immune system makes in response to an infection. The idea is that if you have these antibodies, you previously had Covid-19 — something you might have wondered if you started coughing or felt even a little warm in the past few months.
If you get an antibody test, your doctor or clinic will tell you the results in a couple of days. There are three likely possible outcomes: positive, negative, or equivocal. Seems simple, but interpreting these results can be complicated.
It’s important to note up front that the accuracy of the many different antibody tests on the market varies a lot, and even those that claim upward of 99% accuracy, like the one produced by Abbott, can’t tell you with absolute certainty that you did or didn’t have the disease. Knowing that depends on the prevalence of Covid-19 in your area, which also varies widely depending on where you are: For example, a 99% accurate test in an area with 1% prevalence only gives you results with 50% certainty (to understand the math, check out these really smart explainers in Scientific…
