Children with asymptomatic cases can have active virus for weeks, scientists say

Jessica Renteria is driving a pram with her two children to the Los Angeles Zoo, as it reopens in Los Angeles, California on August 26, 2020, after it was shut down on March 13 due to the coronavirus pandemic. – The reopening of the zoo will see online reservations, limited capacity, required face coverings and improved cleaning procedures for high contact surfaces and toilets in accordance with many social distance guidelines.

Frederic J. Brown | AFP via Getty Images

Children infected with Covid-19 can repel the virus for weeks, even after their symptoms are clear or if they never develop symptoms, according to a new study published Friday in the medical journal JAMA Pediatrics.

Researchers observed 91 children with Covid-19 from February 18 to March 31 across 22 hospitals in South Korea, one of the first countries affected by the coronavirus pandemic.

About 22% of the children, who were under the age of 19, were asymptomatic, meaning they never developed symptoms. The remaining children had symptoms that were found before or shortly after their diagnosis. The duration of symptoms varies, with some children experiencing symptoms for as little as three days, while others have symptoms for nearly three weeks, according to the study.

In general, researchers said the virus was detectable in respiratory tracts of children on average about two-and-a-half weeks.

The researchers found almost half of the children were symptomatic and one-fifth of the asymptomatic children shook even after being tested at three weeks. They added the duration that the asymptomatic children forgot could be even longer because the actual date of their infection is unknown, they said.

“These are striking data,” said Drs. Roberta DeBiasi and Meghan Delane of Children’s National Hospital and Research Institute wrote in an editorial published alongside the study. They were not involved in the investigation.

“These findings are highly relevant to the development of public health strategies to curb and contain prevalence within communities, particularly as affected communities begin their recovery phases,” they said, adding the role of children in spreading the disease needs to be investigated even further.

It remains unclear if the children were contagious when forgetting and, if they were, for how long. The Centers for Disease Control and Prevention has found that Covid-19 patients can recover the virus up to 3 months after contracting, “although at concentrations lower than in disease, in the range where replication-competent “virus has not been found to be reliable and infectiousness is unlikely.”

The authors of the study found that their research was limited. They could not analyze how infectious the children may have been due to the strict quarantine measures of South Korea. Under South Korean rules, patients with Covid-19 must remain in the hospital until they clear their infections.

STAT News reported in a March study that people found mildly ill could not be infectious after 10 days from the onset of symptom.

The study comes Friday as public health officials and experts on infectious disease say it remains unclear what role children play in spreading the coronavirus. It also comes as schools in the US and other parts of the world consider whether it is safe to reopen if the virus spreads rapidly.

Early in the outbreak, researchers said the virus appeared to spare children, while it was particularly serious in parents and those with underlying health conditions.

However, they later found that the apparent lack of children under confirmed cases of coronavirus could also be due to children becoming infected but developing more mild symptoms that are not reported.

A study published in April in JAMA Pediatrics found many children infected with the coronavirus only develop mild symptoms and typically recover within two weeks. The researchers analyzed 1,065 Covid-19 patients, mostly in China, under 19 years of age.

Another report from the Centers for Disease Control and Prevention found that the majority of pediatric patients in the US develop only mild symptoms such as fever or cough.

Although many children can only become mildly or moderately ill from the virus, some children are still at risk of serious or even life-threatening illness.

For example, some people develop Multisystem Inflammatory Syndrome in Children, such as MIS-C, a rare inflammatory condition similar to Kawasaki syndrome. While health officials are still learning what connection Covid-19 has to the condition, children can experience serious complications such as heart dysfunction, shock and kidney damage, according to the CDC.