Coronavirus disease 2019 (COVID-19) patients can still spread the virus after their infection and even once their symptoms clear up, according to a paper published
in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine
Investigators from China and the United States tracked COVID-19 in 16 patients in order to determine how long a patient may still have coronavirus despite being asymptomatic post-infection. The patients were treated in Beijing between Jan. 28 and Feb. 9, 2020. After 2 negative PCR tests, done through throat swabs collective on alternative days, the patients were discharged from the hospital. The median age was 35.5 years but ranged from 3 to 68 years, the study authors added. Most of the patients’ symptoms were fever (in 14 of 16 patients), cough (11/16), pharyngula (5/16), and dyspnea (2/16).
Some of the patients had comorbidities, including diabetes (2/16) and tuberculosis (1/16); the study authors wrote that these comorbidities did not affect the time course of the disease. The 3-year-old patient did not have significantly different clinical course for the disease either compared to the rest of the patients, the study authors added.
The investigators collected travel and possible exposure history from the patients and their records. Of those, 10 patients visited Wuhan and 3 had exposure to a known infected patient. Further, 2 patients had contact with people from Wuhan, though 1 remaining patient had no known exposure to the virus.
All of the patients received medical care to treat COVID-19, according to the study authors. A majority (15/16) were treated with alpha-interferon as well as other drugs including oseltamivir (1/16), lopinavir/ritonavir (11/16), acyclovir (1/16), moxifloxacin (5/16), methylprednisolone (2/16), gamma globulin (2/16), vancomycin (1/16) and meropenem (1/16) either alone or in combination. The investigators also reported that 1 patient required respiratory support involving a ventilator.
After discharge from the hospital, following 2 negative tests, the patients were asked to quarantine at home for 2 weeks. There was a follow-up visit at the hospital after 1 week to confirm the patients’ negative status. From there, the investigators estimated incubation periods based on travel history of potential exposure from the patient.
For all but 1 patient, the incubation period was about 5 days. While the mean duration of symptoms was about 8 days, the study authors found, half of the patients remained viral positive even after no longer showing symptoms.
“The most significant finding from our study is that half of the patients kept shedding the virus even after resolution of their symptoms,” co-lead author Lokesh Sharma, PhD, instructor of medicine, Section of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, Yale School of Medicine, said in a press release
. “More severe infections may have even longer shedding times.”
The study authors admitted that their sample size for this study was small and that their infections were mild. All of the patients recovered, so it is unclear to the study authors if their results are generalizable to a wider population. However, the takeaway message remains, they said:
“If you had mild respiratory symptoms from COVID-19 and were staying at home so as not to infect people, extend your quarantine for another 2 weeks after recovery to ensure that you don't infect other people,” corresponding author Lixin Xie, MD, professor, College of Pulmonary and Critical Care Medicine, Chinese PLA General Hospital, Beijing, recommended in the statement.
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