The novel coronavirus infection is relatively unnoticeable in children, leaving them less likely to get diagnosed. And despite their lack of distinct symptoms, children with COVID-19 can shed the virus for as long as over two weeks, a recent study found, highlighting their potential role in spreading the disease silently in the community.

The study published Aug. 28 in the Journal of the American Medical Association assessed 91 children with COVID-19 in Korea to find that only 8.5 percent of them presented with recognizable symptoms at the time of diagnosis. About one-fifth never ended up developing any symptoms throughout the whole course of the disease.

Pediatric infectious disease specialist Dr. Han Mi-seon, who co-authored the study, said, “Identifying COVID-19 cases in children based on symptoms alone is hard because their symptoms tend to be mild.”

“Considering that most children have ‘silent disease,’ there is no better alternative to enable early detection than extensive testing,” she said. “Had it not for Korea’s large-scale testing regime, over 90 percent of the children’s cases analyzed in the study might have been missed.”

While the study did not look into the infectivity or infectious period of the children’s cases, she added that the viral RNA is detected in the children for “an unexpectedly long time.”

The study said there is evidence of asymptomatic and pre-symptomatic transmission by adults, and that contagiousness of the virus could peak two to three days before the symptoms even manifest.

“These findings illustrate the importance of heightened surveillance to quickly isolate the infected children before they can pass the disease on to individuals with vulnerabilities,” Han said.

The study included a total of 91 children younger than 19 years who had COVID-19 between Feb. 18 and March 31. Their median age was 11 years, and 58 percent were boys.

The children were monitored for an average of 21.9 days, of whom 71 displayed symptoms for a median of 11 days.

Of the symptomatic cases, 46 children (65 percent) had mild cases and 20 children (28 percent) had moderate cases. Two children (3 percent) had a severe case requiring oxygen supplementation. Both of them were in their teens and without underlying diseases.

Fifty-four children (60 percent) had respiratory symptoms such as cough, sputum and nasal congestion. Mild fever, defined as body temperature between 37.5 and 37.9 degrees Celsius, developed in 35 children (39 percent), whereas 27 patients (30 percent) had fever of 38 degrees Celsius or higher. Sixteen children (18 percent) presented with gastrointestinal symptoms including diarrhea and abdominal pain. Twelve children (16 percent) suffered loss of smell or taste.

The most common source of infection was household contact accounting for 57 patients (63 percent), followed by overseas travel for 15 patients (17 percent) and local clusters for 11 patients (12 percent). The point of infection was unknown for four patients (4 percent).

Korea Centers for Disease Control and Prevention’s Monday data show that of the 19,947 confirmed cases, 2.22 percent or 442 were patients under 10, and 5.74 percent or 1,145 were aged between 10-19. None of the patients younger than 20 died.

By Kim Arin (arin@heraldcorp.com)