The early identification of asymptomatic yet infectious cases is vital to curb the 2019 coronavirus (COVID-19) pandemic and to control the disease in the post-pandemic era. In this paper, we propose a fast, inexpensive and high-throughput approach using painless nasal-swab self-collection followed by direct RT-qPCR for the sensitive PCR detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This approach was validated in a large prospective cohort study of 1038 subjects, analysed simultaneously using (1) nasopharyngeal swabs obtained with the assistance of healthcare personnel and analysed by classic two-step RT-qPCR on RNA isolates and (2) nasal swabs obtained by self-collection and analysed with direct RT-qPCR. Of these subjects, 28.6% tested positive for SARS-CoV-2 using nasopharyngeal swab sampling. Our direct RT-qPCR approach for self-collected nasal swabs performed well with results similar to those of the two-step RT-qPCR on RNA isolates, achieving 0.99 positive and 0.98 negative predictive values (cycle threshold [Ct] < 37). Our research also reports on grey-zone viraemia, including samples with near-cut-off Ct values (Ct ≥ 37). In all investigated subjects (n = 20) with grey-zone viraemia, the ultra-small viral load disappeared within hours or days with no symptoms. Overall, this study underscores the importance of painless nasal-swab self-collection and direct RT-qPCR for mass testing during the SARS-CoV-2 pandemic and in the post-pandemic era.

• Klíčová slova
• COVID-19, Mass molecular testing, Nasal mid-turbinate swab, PCR diagnostics, Post-pandemic era, Self-collection,
• MeSH
• COVID-19 diagnóza   prevence a kontrola   MeSH
• diagnostické testy rutinní metody   MeSH
• klinické laboratorní techniky metody   MeSH
• kvantitativní polymerázová řetězová reakce MeSH
• lidé MeSH
• odběr biologického vzorku metody   MeSH
• plošný screening metody   MeSH
• průzkumy a dotazníky MeSH
• samovyšetření metody   MeSH
• SARS-CoV-2 genetika   MeSH
• senzitivita a specificita MeSH
• testování na COVID-19 metody   MeSH
• virová nálož metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• validační studie MeSH