Study suggests children’s potential for ‘silent COVID-19 spread’

SEOUL — The novel coronavirus infection is less apparent in children, leaving them less likely to get recognized and diagnosed. But despite their lack of distinct symptoms, they could shed the virus for as long as over two weeks, a recent study showed, highlighting their potential role in spreading the disease silently.

A study published Aug. 28 in the Journal of the American Medical Association assessed 91 children with COVID-19 to find that 22 percent never developed any symptoms.

Among the 71 children who had symptoms, 25.4 percent were pre-symptomatic — meaning they were not visibly ill at first but eventually got symptoms later. For 66 percent of the symptomatic children, their symptoms were too mild to be noticed at the time of diagnosis.

Pediatric infectious disease specialist Dr. Han Mi-seon, who co-authored the study, said, “Symptom screening fails to identify most COVID-19 cases in children and for children, the viral RNA is detected for an unexpectedly long time.”

“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 in the first few months, 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, there is evidence of asymptomatic and pre-symptomatic transmission by adults. Findings from earlier studies suggest contagiousness of the virus could peak two to three days before the symptoms manifest.

“If children with COVID-19 who don’t present with recognizable symptoms are proven to have transmission potential, their role in transmitting the disease in the community could be much greater than previously thought,” Han said.

A total of 91 children younger than 19 years who had COVID-19 between Feb. 18 and March 31 were included in the study. Their median age was 11 years, and 58 percent were boys. Six children, or 7 percent, had underlying diseases.

The children involved in the study were monitored for an average of 21.9 days, of whom 71 showed 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, who required oxygen supplementation. Both children with severe illness were in their teens and without underlying conditions.

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 travels 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.