March 13, 2020

SARS-CoV-2 Detected in Specimens From Multiple Sites, May Be Transmitted by Extra-Respiratory Routes

By Denise Baez

According to a study published in JAMA, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), can be detected in specimens from other sites, and therefore potentially transmitted in other ways than by respiratory droplets.

The study included 205 patients with specimens (1,070 specimens) collected from 3 hospitals in the Hubei and Shandong provinces and Beijing, China, from January 1, 2020 to February 17, 2020. Pharyngeal swabs were collected from most patients 1 to 3 days after hospital admission. Blood, sputum, feces, urine, and nasal samples were collected throughout the illness. Bronchoalveolar lavage fluid and fibrobronchoscope brush biopsy were sampled from patients with severe illness or undergoing mechanical ventilation.

Bronchoalveolar lavage fluid specimens showed the highest positive rates (93%), followed by sputum (72%), nasal swabs (63%), fibrobronchoscope brush biopsy (46%), pharyngeal swabs (32%), feces (29%), and blood (1%). None of the 72 urine specimens tested positive.

“In this study, SARS-CoV-2 was detected in specimens from multiple sites of 205 patients with COVID-19, with lower respiratory tract samples most often testing positive for the virus,” wrote Wenjie Tan, MD, National Institute for Viral Disease Control and Prevention, Beijing, China, and colleagues. “Importantly, the live virus was detected in feces, implying that SARS-CoV-2 may be transmitted by the fecal route. A small percentage of blood samples had positive polymerase chain reaction test results, suggesting that infection sometimes may be systemic.”

“Transmission of the virus by respiratory and extra-respiratory routes may help explain the rapid spread of disease,” the authors noted. “In addition, testing of specimens from multiple sites may improve the sensitivity and reduce false-negative test results.”

Most of the patients presented with fever, dry cough, and fatigue and 19% of patients had severe illness.

The mean cycle threshold values of all specimen types were more than 30 (<2.6 × 104 copies/mL) except for nasal swabs with a mean cycle threshold value of 24.3 (1.4 × 106 copies/mL), indicating higher viral loads.

Twenty patients had 2 to 6 specimens collected simultaneously. Viral RNA was detected in single specimens from 6 patients (respiratory specimens, feces, or blood), while 7 patients excreted virus in respiratory tract specimens and in feces (n = 5) or blood (n = 2). Live SARS-CoV-2 was observed in the stool sample from 2 patients who did not have diarrhoea.

“Further investigation of patients with detailed temporal and symptom data and consecutively collected specimens from different sites is warranted,” the authors concluded.


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