An in vitro immunochromatographic assay for the direct and qualitative detection of SARS-CoV-2 viral nucleoprotein antigens from nasal and nasopharyngeal secretions from individuals suspected of COVID-19 within 6 days of symptom onset and from individuals without symptoms or other epidemiological reasons to suspect COVID-19 infection, when tested twice over two (or three) days with at least 24 hours (and no more than 36 hours) between tests.