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Patients test positive for COVID-19 after clinical recovery

26 May 2020
Appeared in BioNews 1048

COVID-19 patients are testing positive for genetic elements of SARS-CoV-2, the virus that causes COVID-19, up to 24 days after hospital discharge. 

The study, conducted by researchers at Qingdao Women and Children’s Hospital, Qingdao University, China, aimed to evaluate SARS-CoV-2 viral persistence and included patients who had been hospitalised for COVID-19 and were discharged from hospital before February 27.

Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) tests were performed with nose and anal swab samples from the discharged patients. These tests are capable of detecting ribonucleic acid (RNA), which is the genetic material of the virus.

A relatively small cohort of patients were used for this study, which was published in JAMA Network. Information from 60 individuals in total was taken. Of these 60 subjects, 16.7 percent tested positive for SARS-CoV-2 RNA. A single individual was reported to be testing positive for viral RNA 56 days following the initial disease onset. 

This data supports results from a previous study, published in the Journal of Microbiology, Immunology and Infection, indicating that there is prolonged shedding, replication and release of the virus, in the faeces of patients. It is believed that the positive test results, in this case, are due to persistent viral shedding, rather than reinfection. Viral shedding is when a virus may be contagious and replicates inside your body and is released into the environment.

Professor Babak Javid, principal investigator at Tsinghua University School of Medicine, Beijing, who was not involved in the study, commented: 'The authors suggest that this is viable viral shedding, since they recommend personal protective equipment (PPE) for people in contact with discharged patients. But actually, they never attempted to culture viable virus from any of these patients. Data from other studies, most recently from the South Korea CDC suggests that these positive swab results late into the disease process do NOT represent viable virus and do not pose an infection risk.' 

The authors of the study contend that due to the continued shedding, appropriate PPE for medical staff may be important while collecting recovering patient's plasma, however, they acknowledge that larger-scale observational studies will need to be performed. 

Coronavirus disease 2019 test results after clinical recovery and hospital discharge among patients in China
JAMA Network |  22 May 2020
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