Youngsters emerge as silent threatsTop News | Jane Cheung 7 Apr 2021
Forty percent of Hong Kong children infected with Covid-19 have no symptoms and so could be spreading the virus silently.
Researchers from the Chinese University's faculty of medicine said the virus can remain in a stool for as long as 36 days as they called for caution when allowing two thirds of students to attend face-to-face classes.
Of 11,429 cases on March 25, 926 involved under-18s. They included 201 toddlers aged three or below, including 87 or 43 percent who were asymptomatic compared to 20 percent such cases among adults.
Between March 2020 and last month, 17,500 stool tests were carried out and 22 cases identified. That was equivalent to a rate of 0.13 percent compared to 0.08 percent found in over 20 lockdowns in January and February and 0.006 percent in tests for taxi drivers.
Of the 22 patients, 20 were aged under six and more than 70 percent were asymptomatic.
Overseas studies have suggested children have a significantly higher viral load - ie they are more contagious - than adults in intensive care.
Microbiology department chairman Paul Chan Kay-sheung said: "Their asymptomatic infection could be a result of stronger immunity or cell structures different from adults, enabling them to guard against the coronavirus."
He said kids have a longer incubation period as a stool sample from a two-year-old boy tested positive after 36 days despite his respiratory samples testing positive for only one day.
"Their viral load in stools is medium to high, and the ratio of live virus is extremely high - almost 90 percent are live viruses - and their prolonged virus carriage should not be neglected," he said. So kids "are extremely likely to become hidden carriers."
Chan said as more schools, including preschools, nurseries and kindergartens resume classes, authorities should "pay extra attention to this age group."
If a student is sick for an unknown reason, parents should take the child for a Covid test and stool sampling can be one of the easy options.
Albert Li, head of pediatrics, said parents should be looking out for symptoms including fever, cough and a runny nose in their children.