Children can shed the coronavirus that causes Covid-19, even if they are asymptomatic, or for long after their symptoms have cleared, according to a study which sheds more light on the significance of the paediatric population in the pandemic’s spread.

The study, published in the journal JAMA Pediatrics, followed 91 children at 22 hospitals throughout South Korea, infected with the novel coronavirus SARS-CoV-2, and found that they carried the viral genetic material RNA for a longer period than expected.

“Symptom screening fails to identify most Covid-19 cases in children, and SARSCoV-2 RNA in children is detected for an unexpectedly long time,” the researchers, including those from Seoul National University College of Medicine in South Korea, noted in the study.

In a commentary, published on the study, scientists, including Roberta L DeBiasi from the The George Washington University School of Medicine and Health Sciences in the US, said children may play an important role in the Covid-19 transmission.

“To our knowledge, no prior studies have systematically focused on the frequency of asymptomatic infection in children or the duration of symptoms and viral shedding in both asymptomatic and symptomatic children,” the researchers noted.

According to the study, about 22 per cent never developed symptoms, 20 per cent were initially asymptomatic but developed symptoms later, and 58 per cent were symptomatic at their initial test.

Over the course of the research, the scientists said the hospitals where these children stayed continued to test them every three days on average, providing a picture of how long viral shedding continues over time.

The findings revealed that the duration of symptoms varied widely, from three days to nearly three weeks.

While the virus was detectable for an average of about two-and-a-half weeks in the entire group, a significant portion of the children – about a fifth of the asymptomatic patients, and about half of the symptomatic ones – were still shedding virus at the three week mark, they said.