WEDNESDAY, April 1, 2020 (HealthDay News) -- Some patients with coronavirus disease 2019 (COVID-19) remain positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in sputum or feces after pharyngeal samples become negative, according to a research letter published online March 30 in the Annals of Internal Medicine.
Chen Chen, Ph.D., from Capital Medical University in Beijing, and colleagues examined the results of real-time quantitative fluorescence polymerase chain reaction (RT-qPCR) testing for SARS-CoV-2 RNA of sputum and fecal samples from a group of patients after conversion of the pharyngeal samples from positive to negative.
The researchers found that 22 of 133 patients admitted with COVID-19 from Jan. 20 to Feb. 27, 2020, had an initial or follow-up positive sputum or fecal sample paired with a follow-up negative pharyngeal sample. Eighteen of these patients were aged 15 to 65 years and four were children. The most common initial symptom at onset was fever, and five patients had at least one preexisting medical condition. A total of 545 specimens were collected from these patients, including 209, 262, and 74 pharyngeal, sputum, and feces samples, respectively. Sputum and feces samples remained positive for SARS-CoV-2 on RT-qPCR up to 39 and 13 days, respectively, after pharyngeal samples were negative.
"It is important to emphasize, however, that it is not known whether the positive RT-qPCR results for SARS-CoV2 observed here indicate that a patient continues to pose a risk for infection to others," the authors write.