Could Patients be Carriers of COVID-19 Post Recovery?
By Rituparna Ganguly, Ph.D.
Edited by Rajaneesh K. Gopinath, Ph.D.
A recently published research letter in JAMA is raising concerns after it reported four patients testing positive for the COVID-19 causing coronavirus, 5-13 days after their recovery. These patients, who are Chinese medical professionals contracted the disease through work-related exposure and were being treated at the Zhongnan Hospital at Wuhan University. Patients had a combination of fever and cough at the onset of the disease. Although their symptoms were mild to moderate, RT-PCR based diagnostic testing on throat swabs showed positive viral nucleotides and chest CT (Computed tomography) imaging demonstrated positive lesions in the lungs.
All four of them were treated with antiviral drug oseltamivir (same as the composition of Tamiflu) at a dose of 75 mg every 12 hours. The patients recovered from their infection in a span of 12-32 days on average. All clinical and radiological symptoms were resolved in 3 patients, while one continued to show signs of chest lesions. Before their hospital discharge, all of them tested negative for RT-PCR and were advised to remain under home quarantine for 5 additional days. Surprisingly, 5-13 days since their discharge, follow up RT-PCR tests came out positive in these patients. There was no indication of new exposures and family members were uninfected. Apart from the positive RT-PCR diagnosis, there were no other symptoms.
This interesting finding suggests that recovered COVID-19 patients might still be carriers and potentially infect others. This is unanticipated since patients show no signs of infection and cleared diagnostic testing and radiological evaluations. This case is not an anomaly since the Japanese health ministry also reported the first case in Japan where a 40-year-old woman patient tested positive after hospital discharge. Another report from China confirmed that 14% of COVID-19 survivors tested positive again. A similar observation was made in a study conducted in 10 COVID-19 positive children, where rectal swabs of five subjects confirmed viral presence long after their nasopharyngeal swabs or CT imaging turned negative. However, there was no evidence to show that the viruses retained were capable of replication.
The current pandemic is a stress test to the medical infrastructures around the world and hospital systems are overwhelmed with increasing patients as it is. A study published in The Lancet journal has reported that the longest observed time span for viral shedding in survivors is 37 days. At present, the discharge criteria of patients include no fever for 3 days, improved respiratory symptoms, two consecutive negative RT-PCR results, and improved lesions in CT imaging. This report indicates the importance of reevaluating follow-up protocols and calls for patient monitoring for a longer duration. More importantly, it is imperative to determine whether the residual viruses in the body after recovery are infectious, a piece of information that would help us flatten the curve.
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