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Infectious Diseases

08 April 2020

US study finds Covid-19 seldom severe in kids

American and Chinese studies found that children under the age of 18 are far less likely to even be diagnosed with Covid-19 than adults.

Mirroring findings from a similar study in China, the first comprehensive tally of coronavirus infection in American children shows it's much less likely to cause severe illness.

Children under the age of 18 are far less likely to even be diagnosed with Covid-19 than adults. Although people under the age of 18 make up 22% of the US population, they made up just 1.7% of cases recorded between 12 February and 2 April, the new study found.

Even if kids were made ill by the new coronavirus, that illness was typically mild, said a team led by Lucy McNamara, of the US Centers for Disease Control and Prevention's Covid-19 Response Team.

Just under 6% of kids with Covid-19 ended up in the hospital, the study found, compared to 10% of adults aged 18 to 64.

Underlying medical condition

And while every paediatric death is a tragedy, only three of the 2 572 children with Covid-19 covered by the study died, the team reported.

Even the usual symptoms of Covid-19 appear less frequently in kids, McNamara's team noted.

"Relatively few children with Covid-19 are hospitalised, and fewer children than adults experienced fever, cough or shortness of breath," the CDC group found.

When cases among kids are severe, most often the child has an underlying medical condition, such as asthma, heart ailments or suppressed immune systems (for example, due to cancer therapies), the study authors noted.

Among nearly 300 cases where data on the child's other medical history was available, "28 of 37 (77%) hospitalised patients, including all six patients admitted to an ICU, had one or more underlying medical conditions," the CDC team reported.

The findings are consistent with a prior study of paediatric Covid-19 cases in China, where the pandemic began, the researchers said.

Dr Lorry Rubin directs paediatric infectious disease at Cohen Children's Medical Center in New Hyde Park, New York. Reading over the CDC report, he agreed that "the likelihood of a child getting seriously ill with Covid-19 is much lower than in adults".

Kids mostly protected

When serious illness does occur, it's usually linked to another chronic health condition, Rubin explained. Very rarely, an otherwise healthy child may become severely ill with Covid-19 – in these cases it may be "related to a more robust [excessive] inflammatory response to the virus than other children, to which the children are genetically predisposed," he theorised.

Another expert noted that many more children are probably infected with coronavirus than is realised.

"I want to emphasise that there is an enormous number of kids probably getting this disease that are asymptomatic with very mild symptoms," said Dr Eric Cioe Pena, director of global health at Northwell Health, in New Hyde Park, New York. "Certainly, there isn't a very high risk of mortality in this age group, and I want to reassure people of that," he said.

While rare and very tragic deaths do occur, "kids are mostly protected from this," he said, "and that's really the lesson we learned."

But McNamara's team stressed that even if that is so, social distancing, handwashing and other preventive measures must extend to children as well, because they can unwittingly pass on the virus to their more vulnerable elders.

Doing so will "protect the health care system from being overloaded, and protect older adults and persons of any age," the CDC team wrote.

The new report was published in the CDC's Morbidity and Mortality Weekly Report.

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