Clinicians from the Institute of Infectious Diseases at Beijing Ditan Hospital, Capital Medical University found that some patients had positive real-time fluorescence polymerase chain reaction (RT-PCR) test results for SARS-CoV-2 in the sputum or feces after the pharyngeal swabs became negative. Pharyngeal swabs are widely used to determine the appropriateness for a patient’s discharge from the hospital and/or whether isolation continues to be required. These findings raise concerns over whether patients with negative pharyngeal swabs are truly virus-free or if sampling of additional body sites might be needed.
The clinicians retrospectively identified a convenience sample of patients admitted to Beijing Ditan Hospital, Capital Medical University with a diagnosis of COVID-19 and paired RT-PCR testing of pharyngeal swabs with either sputum or feces. Among 133 patients admitted with COVID-19 from January 20 to February 27, 2020, the authors identified 22 with an initial or follow-up positive sputum or fecal samples paired with a follow-up negative pharyngeal sample. RT-PCR positive for SARS-CoV2 of sputum and feces was seen up to 39 and 13 days, respectively, after the obtained pharyngeal samples were negative.
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