PRC graphic (IMAGE) Johns Hopkins Medicine Caption In what is believed to be the largest prospective study of its kind to date — involving some 6,000 patients seen at a field hospital set up at the Baltimore Convention Center (seen in background) — researchers at Johns Hopkins Medicine and collaborators report that a rapid antigen detection test for SARS-CoV-2, the virus that causes COVID-19, proved more effective than expected when compared with virus detection rates using the established standard test, the polymerase chain reaction (PCR) assay. Credit Graphic created by M.E. Newman, Johns Hopkins Medicine, using public domain images. Usage Restrictions none License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.