Children carry coronavirus in their noses and throats for weeks, even if they don’t show any symptoms, researchers in South Korea reported Friday.
Although their study does not necessarily demonstrate that children are transmitting the virus to others, they suggested this might be responsible for “silent spread’ of the virus in communities.
"In this case series study, inapparent infections in children may have been associated with silent COVID-19 transmission in the community," the researchers, from various institutions in South Korea, wrote in the study.
The study, published in the journal JAMA Pediatrics on Friday, included data on 91 children in South Korea diagnosed with Covid-19 between Feb. 18 and March 31.
Among those patients, 20 of them — or 22% — did not show any obvious symptoms and remained asymptomatic throughout the study. Other patients experienced fever, cough, diarrhea, abdominal pain and loss of smell or taste, among other symptoms. The duration of their symptoms appeared to vary, ranging from one to 36 days.
But genetic material from the virus was detectable in the children for a mean of 17.6 days. Virus could be found in the children who had no symptoms for 14 days on average.
This doesn’t necessarily mean the children were spreading virus, Calum Semple, a professor in child health and outbreak medicine at the University of Liverpool who was not involved in the study, said in a statement distributed by the UK-based Science Media Center.
“The presence of the virus genetic material in swabs the respiratory tract need not equate with transmission, particularly in people who do not have important symptoms such as cough and sneeze,” Semple said.
It's possible that virus persisted in the children for even longer than the time documented. And more research also is needed to determine whether similar findings would emerge among a larger group of children from other parts of the world.
The data showed that only 8.5% of those patients with symptoms were diagnosed with Covid-19 at the time their symptoms began. Most — 66.2% — of those with symptoms had symptoms that were not recognized before they were diagnosed and 25.4% developed symptoms after they were diagnosed.