Mechanically ventilated patients shed high titre live SARS-CoV2 for extended periods from both the upper and lower respiratory tract


Clinical Infectious Diseases

Contributing to research themes:

Background: SARS-CoV-2 infection can lead to severe acute respiratory distress syndrome needing intensive care admission and may lead to death. As a virus that transmits by respiratory droplets and aerosols, determining the duration of viable virus shedding from the respiratory tract is critical for patient prognosis, and informs infection control measures both within healthcare settings and the public domain.

Methods: We prospectively examined upper and lower airway respiratory secretions for both viral RNA and infectious virions in mechanically ventilated patients admitted to the intensive care unit of the University Hospital of Wales. Samples were taken from the oral cavity (saliva), oropharynx (sub-glottic aspirate), or lower respiratory tract (non-directed bronchoalveolar lavage (NBL) or bronchoalveolar lavage (BAL)) and analyzed by both qPCR and plaque assay.

Results: 117 samples were obtained from 25 patients. qPCR showed extremely high rates of positivity across all sample types, however live virus was far more common in saliva (68%) than in BAL/NBAL (32%). Average titres of live virus were higher in subglottic aspirates (4.5x10 7) than in saliva (2.2x10 6) or BAL/NBAL (8.5x10 6) and reached >10 8 PFU/ml in some samples. The longest duration of shedding was 98 days, while most patients (14/25) shed live virus for 20 days or longer.

Conclusions: Intensive care unit patients infected with SARS-CoV-2 can shed high titres of virus both in the upper and lower respiratory tract and tend to be prolonged shedders. This information is important for decision making around cohorting patients, de-escalation of PPE, and undertaking potential aerosol generating procedures.

Author list:

Zack Saud, Mark Ponsford, Kirsten Bentley, Jade M Cole, Manish Pandey, Stephen Jolles, Chris Fegan, Ian Humphreys, Matt P Wise, Richard Stanton