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Recurrence of positive SARS-CoV-2 viral RNA in recovered COVID-19 patients during medical isolation observation

Our take —

This study demonstrated that approximately 10% of symptomatic hospitalized patients had respiratory or fecal samples with evidence of SARS-CoV-2 RNA 7 to 14+ days following hospital discharge, despite lack of COVID-19 symptoms. Detection of viral RNA following initial recovery is likely not uncommon, but it remains unclear if the detectable virus is infectious, if the treatment the patients received in the hospital altered the natural history of infection, and if this pattern would be similar in asymptomatic infections.

Study design

Prospective Cohort

Study population and setting

All patients (n = 182) diagnosed with COVID-19 in Shenzhen City, China at Samii Medical Center who had recovered and met the discharge criteria (no fever 3+ days, absence of respiratory symptoms and improved chest CT, and 2 negative PCR tests at least 24 hours apart) by February 21, 2020 stayed in medical isolation for observation for 14 additional days, during which time they received viral RNA testing of nasal and anal swabs on days 7 and 14 and blood on day 7. 147 of the patients underwent serological antibody testing following encouragement from medical providers. 39 of the patients recovered from severe disease, and 143 had recovered from mild or moderate disease.

Summary of Main Findings

No patients developed any recurrence of COVID-19 symptoms during the 14 day follow-up period. 20 patients had one additional positive PCR test during the 14 day isolation period (13 on day 7, and 7 on day 14). Those with a recurrence of positive RNA following initial recovery were more likely to have shorter hospital stays, less severe disease, and were younger than 18 years. Among the subset of patients who underwent antibody testing, there were no significant differences in antibody titer between those who re-tested positive and those who did not, and all 14 re-positive patients had detectable IgG and IgA antibodies prior to the positive PCR result. Among patients who re-tested positive, all eventually tested negative except for an 8-year old boy who first tested positive on throat swab on Feb 1 and whose last anal swab test during follow-up on March 20 still had evidence of viral RNA.

Study Strengths

The authors followed all individuals in this hospital over time after resolution of illness for recurrence of samples with evidence of viral RNA. They were able to test multiple types of swabs from both mild/moderate and severely infected patients.


There is a lack of information on treatment, which is referred to multiple times in the article without further details, and may impact the natural history of infection. Additionally, this study only included individuals with disease; therefore, these results do not provide any insight into recurrence among asymptomatic individuals. We also do not know how the viral titers upon re-testing correlated with those during disease, which may be important in the natural history of infection. Finally, we do not know if the RNA detected was infectious, nor if any of the antibodies detected were neutralizing.

Value added

This study demonstrated that >10% of patients hospitalized in China with COVID-19 in a single hospital in China re-tested positive for SARS-CoV-2 RNA from either nasopharyngeal or anal swabs 7 to 14+ days after meeting the criteria for discharge, including 2 negative RNA tests at least 24 hours apart. Patients who re-tested positive had slightly shorter hospital stays and were more likely to be <18 years old, and all patients with recurrent viral RNA were antibody positive at the time of discharge.

This review was posted on: 27 September 2020