Aug. 20 (UPI) -- Asymptomatic young people could be "silent spreaders" of COVID-19, with higher levels of the virus in their systems than hospitalized adults, a study published Thursday by the Journal of Pediatrics found.
In the study of 192 newborns to 22-year-olds, 49 tested positive for the virus and an additional 18 had late-onset symptoms of the disease, researchers said.
Findings from nasal and throat swabs revealed that infected children -- even those with no outward symptoms of COVID-19 -- had significantly higher levels of the virus in their airways than hospitalized adults who were receiving treatment in the intensive care unit, the researchers said.
"The potential role that children could play in this pandemic should not be underestimated," study co-author Dr. Lael Yonker, told UPI.
"Even though children generally only develop mild illness with acute infection, they have the potential to carry and spread high levels of virus [to] individuals [who] may be more severely affected," said Yonker, who is director of the Cystic Fibrosis Center at Massachusetts General Hospital.
The contagion of children infected with COVID-19 has been unclear. Evidence from several European countries suggests that the virus can spread among school-age children, according to a report by the University of Washington.
However, just two of 34 households with multiple lab-confirmed COVID-19 infections in Chicago had cases of child-to-child transmission, and only two others had instances of child-to-adult transmission, a study published in June by the Journal of the Pediatric Infectious Diseases Society found.
Yonker and her colleagues acknowledged they were "surprised" to find that children had such high viral loads, or levels of the virus in their system, adding that the risk of contagion increases as viral loads rise.
The findings come as many regions across the country are reopening schools, daycare centers and other facilities in which large numbers of children congregate and have close contact with teachers and staff members.
Although children with COVID-19 are not as likely to become as seriously ill as adults, they can spread infection and bring the virus into their homes as asymptomatic carriers or carriers with few symptoms, making them potential "silent spreaders," the researchers said.
For schools and others facilities that reopen, infection control measures, including social distancing, universal mask wearing, effective hand-washing protocols and a combination of remote and in-person learning, as well as routine COVID-19 screening are critical, they said.
"Children are not spared from infection or severe illness related to COVID-19," Yonker told UPI. "We hope policymakers will use this data to implement safety precautions to ensure the safe opening of schools."