International Journal of Infectious Diseases (Jan 2021)
Residual SARS-CoV-2 RNA in nasal swabs of convalescent COVID-19 patients: Is prolonged quarantine always justified?
- Antonio Piralla,
- Matteo Ricchi,
- Maria Grazia Cusi,
- Paola Prati,
- Nadia Vicari,
- Giada Scarsi,
- Claudia Gandolfo,
- Gabriele Anichini,
- Chiara Terrosi,
- Elena Percivalle,
- Edoardo Vecchio Nepita,
- Federica Bergami,
- Monica Tallarita,
- Raffaella Di Martino,
- Alessandro Ferrari,
- Francesca Rovida,
- Giovanna Lunghi,
- Roberta Schiavo,
- Fausto Baldanti
Affiliations
- Antonio Piralla
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
- Matteo Ricchi
- Diagnostic Section of Piacenza, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, (IZSLER), Piacenza, Italy
- Maria Grazia Cusi
- Microbiology and Virology Unit, S. Maria delle Scotte University Hospital of Siena, Siena, Italy; Virology Unit, Department of Medical Biotechnologies, University of Siena, Siena, Italy
- Paola Prati
- Diagnostic Section of Pavia, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna (IZSLER), Pavia, Italy
- Nadia Vicari
- Diagnostic Section of Pavia, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna (IZSLER), Pavia, Italy
- Giada Scarsi
- Diagnostic Section of Pavia, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna (IZSLER), Pavia, Italy
- Claudia Gandolfo
- Microbiology and Virology Unit, S. Maria delle Scotte University Hospital of Siena, Siena, Italy; Virology Unit, Department of Medical Biotechnologies, University of Siena, Siena, Italy
- Gabriele Anichini
- Virology Unit, Department of Medical Biotechnologies, University of Siena, Siena, Italy
- Chiara Terrosi
- Virology Unit, Department of Medical Biotechnologies, University of Siena, Siena, Italy
- Elena Percivalle
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
- Edoardo Vecchio Nepita
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
- Federica Bergami
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
- Monica Tallarita
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
- Raffaella Di Martino
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
- Alessandro Ferrari
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
- Francesca Rovida
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
- Giovanna Lunghi
- Virology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Roberta Schiavo
- Microbiology Unit, Clinical Pathology Department, Guglielmo da Saliceto Hospital, Piacenza, Italy
- Fausto Baldanti
- Molecular Virology Unit, Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy; Corresponding author at: Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy.
- Journal volume & issue
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Vol. 102
pp. 299 – 302
Abstract
Real-time reverse transcription PCR is currently the most sensitive method to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Defining whether a patient could be contagious or not contagious in the presence of residual SARS-CoV-2 RNA is of extreme importance in the context of public health. In this prospective multicenter study, virus isolation was prospectively attempted in 387 nasal swabs from clinically recovered patients showing low viral load (quantification cycle, Cq, value greater than 30). The median Cq value was 36.8 (range 30.0–39.4). Overall, a cytopathic effect was detected in nine samples, corresponding to a culture positivity rate of 2.3% (9/387). The results of this study help to dissect true virus replication and residual viral RNA detection in recovered patients.
