A new study suggests people affected by coronavirus may be contagious for several days after their symptoms disappear.
A team of researchers from Yale University School of Medicine in a US state found that about half the COVID-19 patients in China carried the virus even after they appeared to have recovered.
Some were infectious for up to eight days after their symptoms, including fevers and coughs, had alleviated.
The researchers said the findings of the study, published in the American Journal of Respiratory and Critical Care Medicine, provide evidence that patients should extend their isolation beyond the recommended 14 days so as not to infect others.
The researchers observed 16 patients with mild cases of the virus for their study. They had all been admitted to the Treatment Center of PLA General Hospital in Beijing between January 28 and February 9.
Coughing, fever, pain in the pharynx (the membrane that connects the nose and mouth to the esophagus) and shortness of breath were among primary symptoms. The team took throat swabs of all the patients on alternate days and analysed them for signs of the virus.
These adults were discharged after they received two consecutive negative tests.
“The most significant finding from our study is that half of the patients kept shedding the virus even after resolution of their symptoms,” said co-lead author Dr Lokesh Sharma, an instructor at Yale School of Medicine.
“More severe infections may have even longer shedding times.”
The incubation period, from infection to the onset of symptoms, was five days in all but one patient.
Patients had symptoms for an average of eight days and remained contagious for one to eight days after symptoms ended.
Corresponding author Dr Lixin Xie, a professor at PLA General Hospital in Beijing, suggested people self-isolate for longer.
“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 two weeks after recovery to ensure that you don’t infect other people,” he said.
The authors said despite the small-scale of patients studied, that the findings suggest patients who have appeared to recover could spread the disease.
“COVID-19 patients can be infectious even after their symptomatic recovery, so treat the asymptomatic/recently recovered patients as carefully as symptomatic patient,’” they wrote.