One year into the coronavirus disease 2019 (COVID‐19) pandemic, diagnosticstrategies, although central for contact tracing and other preventive measures, arestill limited. To meet the global demand, lower cost and faster antigen tests forsevere acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) detection are aconvenient alternative to the gold standard reverse transcription‐polymerase chainreaction (RT‐PCR) assay. We tested laboratory‐based RT‐PCR RNA detection andtwo rapid antigen detection (RAD) tests, based on the immunochromatography testfor nucleocapsid protein of SARS‐CoV‐2 (COVID‐19 Ag ECO Test, ECO Diagnóstica,and Panbio COVID‐19 Ag Rapid Test Abbott). Paired collection and testing weredone in a small prospective open study in three clinical services in São Paulo,constituted of mostly symptomatic volunteers at collection (97%, 109/112) for amedian of 4 days (interquartile range: 3–6), ranging from 1 to 30. Among the108 paired RT‐PCR/RAD tests, results were concordant in 96.4% (101/108). Thetest's performance was comparable, with an overall sensitivity of 87% and aspecificity of 96%. These observations add to other data that suggest that antigentests may provide reasonable sensitivity and specificity and deserve a role toimprove testing strategies, especially in resource‐limited settings.