Patients with the new coronavirus keep the pathogen in their respiratory tract for as long as 37 days, a new study found, suggesting they could remain infectious for many weeks.
In yet another sign of how difficult the pandemic may be to contain, doctors in China detected the virus's RNA in respiratory samples from survivors for a median of 20 days after they became infected, they wrote in an article published in the Lancet medical journal.
The new coronavirus has spread to 118 countries and infected about 125,000 people since first emerging in Wuhan, China, at the end of last year, evading drastic efforts by local authorities and subsequent containment attempts in other nations.
The findings have "important implications for both patient isolation decision-making and guidance around the length of antiviral treatment," Fei Zhou from the Chinese Academy of Medical Sciences and the other authors wrote.
Currently, the recommended isolation period after exposure is 14 days to avoid spreading the virus. But if people remain contagious long after their symptoms have vanished, they may unwittingly propagate the pathogen after they return from quarantine.
By comparison, only a third of patients with SARS still harbored the virus in their respiratory tract after as long as four weeks, the Chinese scientists said. They studied the medical records and laboratory data from 191 Covid-19 patients treated at Jinyintan Hospital and Wuhan Pulmonary Hospital, including 54 who died from the infection.
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