University of Michigan researchers reporting in JAMA Network Open outline a non-invasive, breath-based strategy for detecting Delta variant SARS-CoV-2 based on exhaled volatile organic compounds (VOCs). With the help of a portable gas chromatography device, the team searched for VOC markers in more than 200 breath samples collected between the spring of 2021 and May 2022 from 167 individuals with or without PCR-confirmed COVID-19 infections, focusing in on four VOCs that could differentiate between Delta SARS-CoV-2 infections and non-COVID-19 illness with nearly 95 percent accuracy. In contrast, that VOC set had just over 82 percent accuracy for picking up COVID-19 cases caused by the Omicron variant of SARS-CoV-2, the authors note. "The emergence of the Omicron variant in 2022 substantially affected the VOC profiles," they caution, "requiring a different set of VOCs to distinguish between the Omicron variant and non-COVID-19 illness."