In a large prospective study of just over 1,000 patients ages 17 and younger who were seen at the Baltimore Convention Center Field Hospital (BCCFH) testing site during a seven-month period last year, researchers from Johns Hopkins Medicine and collaborating institutions report that a rapid antigen test for SARS-CoV-2 — the virus that causes COVID-19 — proved highly accurate when compared to the established standard virus detection method: the polymerase chain reaction (PCR).