COVID-19 patients may test positive for virus weeks after recovery

Last Updated: 2020-05-27

By Anne Harding

NEW YORK (Reuters Health) - Some recovered coronavirus disease 2019 (COVID-19) patients test positive for SARS-CoV-2 nucleic acid after hospital discharge, according to new findings.

"Our study reported positive RT-PCR test results for SARS-CoV-2 among discharged patients, with 8.3% positive nasopharyngeal swab results and 10.0% positive anal swab results, including 1 patient positive for both swab samples," Dr. Pa Wu of Hunan Normal University in Changsha, China, told Reuters Health by email.

One patient had donated plasma to critically ill patients, Dr. Wu noted. "Considering the unfavorable therapeutic effect of the convalescent plasma, we suggest that the effects of convalescent plasma from clinically recovered patients with re-detected viral shedding to be evaluated separately."

The researchers analyzed samples from 58 recovered COVID-19 patients after two previously hospitalized patients were readmitted to their hospital with symptoms and tested positive for SARS-CoV-2.

Five patients had positive nasopharyngeal swab results, the researchers report in in JAMA Network Open. Six had positive anal swabs, and one patient tested positive on both swab samples. Patients tested positive from four to 24 days after their initial discharge.

The two index patients had occasional cough, but none of the other eight patients who tested positive had symptoms. The symptomatic patients were both older than 70 and had several comorbidities. The second patient had viral shedding 56 days after first becoming ill.

The nine staff members who collected plasma for critically ill patients from one of the patients in the study did not have adequate personal protective equipment and were quarantined for two weeks, but none developed infection.

The recovered patients who tested positive did not infect others after they had been discharged, Dr. Wu noted. "Follow-up studies including large cohort of discharged patients and potential infectivity of these patients are projects of importance to us and we are looking forward to international cooperation," the researcher said.

"Additionally, we are currently investigating the serum antibody composition of recovered COVID-19 patients, trying to figure out why some patients recovered soon after infection while others had long viral shedding period despite positive anti-SARS-CoV-2 antibody results," Dr. Wu said.

"The virus is very cunning. After persistent negative RT-PCR test results for SARS-CoV-2 over four times, some patients re-tested positive for the virus nucleic acid," the researcher noted. "In addition, two patients, who were older than 70 years with multiple underlying medical conditions, were discharged and re-admitted to the hospital multiple times following the RT-PCR test results. Extra patience and attention are needed in combating COVID-19."

SOURCE: https://bit.ly/3ghTkJU JAMA Network Open, online May 22, 2020.