An analysis by doctors at Children’s National Hospital in Washington calls into question the commonly held — and comforting — assumption that children seem to escape the novel coronavirus’s more serious impacts.

“We have been ready, but frankly, surprised,” Roberta DeBiasi, the hospital’s infectious disease division chief, said Friday. “We are actually having a significant number of admissions and critical care admissions.”

Since the virus has begun sweeping through American cities, leading to economic downturn and social distancing measures, public health officials have repeatedly warned that the elderly are most at risk.

While from a small sample size, the data from Children’s National suggests some kids may not be as immune to the virus as once assumed. Between March 15 and April 22, Children’s National saw 105 children who were sick with the coronavirus. Twenty-eight required hospitalization, or about 27 percent, DeBiasi said. The hospital has yet to see a fatality related to the virus.

“Of the 28 that were hospitalized, about three-quarters of them are what we call regular hospitalization, while a quarter of them needed critical care in our intensive care unit,” she said.

According to DeBiasi, statistics out of Asia showed that children there made up a small slice — 1 or 2 percent — of the infected. Infections in Seattle and California in February and early March seemed to back up the assumption — kids weren’t filling hospitals beds because of the virus.

DeBiasi said Children’s is seeing more young patients than they expected given those reports.

“It’s nothing like the burden on the elderly adults, we’re not saying that,” DeBiasi said. “But it’s clear that it’s not slowing down. We’re having more and more cases, and we’ve steadily had admissions each day, both to the critical care and the noncritical care.”

She added: “We want people to be aware that it’s true children aren’t as heavily affected as elderly adults, but it does happen, and you need to be prepared, because it’s not a rare thing either.”

Although the hospital’s findings are a rough draft that will require more study, the data does fit into a larger national trend that has troubled the segment of the medical world focused on the young.

“I think the one thing we would all agree on in pediatrics is the impact on children has not been emphasized enough,” said Mark R. Schleiss, a professor of pediatrics at the University of Minnesota Medical School who has been studying the pandemic’s effect on young patients across the country. “If mortality is your metric, thank God we don’t see that in kids. But we do see disease.”

The 105 patients from Children’s National range in age from newborns to 25-year-olds. “It’s the kids under a year of age, or the kids over 15 years of age that are more likely to get hospitalized,” DeBiasi said. “Particularly in the critically ill group, it’s the kids over 15, so the older age group.”

In terms of gender, DeBiasi said the hospital has seen an equal breakdown between male and female across the total cases. But girls are slightly more likely to be hospitalized, although boys make up the majority of critical care hospitalizations.

The hospital has also looked at how underlying medical conditions factored into their 105 covid-19 patients. According to DeBiasi, overall “40 to 43 percent of the kids had an underlying condition. So that means conversely about 57-60 percent are normal kids.”

Seventy percent of the children hospitalized had an underlying condition.

“The take-home point is that yes, it is more likely you are going to be hospitalized or put in critical care if you have an underlying problem,” she said.

DeBiasi stressed that more analysis will be needed to dig into why more children are getting sicker in the D.C. area than on the West Coast. “It’s definitely different,” she said. “But we’re not sure yet why. Is it because we have a more densely packed population? Does it have to do with ethnic or racial representation?”

According to DeBiasi, experts believe the cases that arrived on the East Coast were from Europe, whereas the West Coast coronavirus is believed to have arrived from China.

“From my knowledge, there is no clear major genetic differences between the strands, but that would be another difference to look at one day.”

The data from Children’s National also point to one of the more troubling aspects of the entire pandemic — a development that has frustrated efforts to accurately diagnosis patients.

When the virus initially crashed onto American shores, public health officials advised a high fever and cough were the two main symptoms. But the following weeks have shown the virus presents itself in more ways than initially thought, including stomach issues, particularly in kids.

DeBiasi said of the fever-plus-cough formulation, only 51 percent of Children’s National patients had both symptoms. “So 49 percent of them don’t have both,” she said. “There are also a lot of kids that have diarrhea, and it’s a little harder to tease that out, because if parents are coming in for respiratory symptoms, they don’t necessarily focus on the diarrhea.”

The University of Minnesota’s Schleiss said that unlike “a lot of standard winter respiratory viruses” that target children, covid-19 is a virus that enters the bloodstream. “It can go anywhere in the body and do anything,” he said, explaining the range of symptoms. “It makes covid-19 more interesting and more scary.”

Schleiss noted that the emphasis on covid-19-positive children is particularly important from a public health standpoint because kids don’t live alone. They often become the vector through which the virus jumps to other family members. If the coronavirus is making more kids sick nationally, it’s going to directly impact the adult population.

“We can’t ignore the transmission of children,” he said. “Children often live in households with adults and the elderly. We already know this virus disproportionately targets African American families, and those are families where there might be multiple generations in one household, or less opportunities for social distancing. As pediatricians, we have to see that the diagnosis of a child is really the diagnosis of a family.”