When the pandemic began, antibody testing was looked to as the kind of ace in the hole that would not only resolve the COVID-19 testing shortage fast and for good but also pave the way for society to reopen. Regrettably, those aspirations have not come to fruition. Although the lack of sensitivity has been the main stumbling block, the effectiveness of SARS-CoV-2 antibodies tests has also been hampered by lack of standardization. But a new collaboration teaming the U.S. Centers for Disease Control and Prevention (CDC), the European Commission Joint Research Centre and testing giant Siemens Healthineers has set out to fix that problem. The Diagnostic Challenge To deliver more effective treatment and achieve better outcomes, clinicians must be able to track patients’ antibody level concentrations and make comparisons regardless of test methods and manufacturers. But while they all take the approach of diagnosing COVID-19 by detecting the antibodies the body produces to combat the virus that causes it, different tests target different SARS-CoV-2 proteins. This disparity among targets, which include the spike protein, S1/S2, S1 RBD and N protein found in different regions of the virus, makes comparison between and among different tests an exercise in apples to oranges. […]