Fewer kids may be carrying coronavirus without symptoms than believed, study says

(HealthDay)—Are infected-but-healthy children major "silent spreaders" of the new coronavirus? New research out of northern Italy, once a COVID-19 hotspot, suggests they might not be.

Rigorous COVID-19 testing of children and adults admitted to a hospital in Milan for reasons other than coronavirus found that just over 1% of kids tested positive for SARS-CoV-2, compared to more than 9% of adults.

That suggests a very low rate of asymptomatic infection among children, and does "not support the hypothesis that children are at higher risk of carrying SARS-CoV-2 asymptomatically than adults," the researchers reported in the Sept. 14 online edition of JAMA Pediatrics.

One U.S. expert in infectious disease found the report encouraging.

"Since the start of the pandemic it has been very difficult to determine what the actual role of children in the spread of the virus is," said Dr. Amesh Adalja, senior scholar at the Center for Health Security at Johns Hopkins University, in Baltimore.

"It is becoming clear that they do not amplify this virus the way they do influenza when it comes to community spread," Adalja said.

In the new study, physicians led by Dr. Carlo Agostoni, of the Ca'Granda Foundation Maggiore Polyclinic Hospital in Milan, conducted two sets of nasal swab tests, up to two days apart, on 214 newly admitted patients.

Eighty-three of these new admissions were children and 131 were adults. All were admitted to the hospital in March and April, at the height of northern Italy's COVID-19 outbreak. However, all of the patients were admitted for reasons unconnected to COVID-19, and none had shown any symptoms of the illness.

So how many were secretly carrying the virus nonetheless? Based on the swab tests, only 1.2% of the pediatric patients turned up positive for infection, compared to 9.2% of adults.

The low rate of carriage among kids in a city with a burgeoning number of COVID-19 cases suggests "that [children's] role as facilitators of the spreading of SARS-CoV-2 infection could be reconsidered," the study authors wrote.

Still, the researchers stressed that this is a small sample from just one hospital, so the findings shouldn't be considered definitive.

And of course community outbreaks of COVID-19 tied to asymptomatic but infected children are happening in the United States. On Friday, researchers from the U.S. Centers for Disease Control and Prevention issued a report on a cluster of cases originating from two Salt Lake City day care facilities. The report found that 12 youngsters infected with coronavirus (only three showed any symptoms) enrolled at two day care centers easily passed SARS-CoV-2 to at least 12 family members, one of whom ended up hospitalized.

So as millions of children head back to school, uncertainty as to their role in the spread of COVID-19 continues, Adalja said.

"The new study provides further evidence that children are less frequently infected than adults, even asymptomatically," he said, but "the important question to definitively answer remains: Are they major drivers of outbreaks?"

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