At first, it was just a handful of puzzling cases, Jane Newburger recalled. Other doctors had contacted her describing children with COVID-19 coming to emergency rooms in bad shape with a kind of inflammatory shock syndrome affecting multiple organs.
Some were screaming from stomach pain. Others had bubbles, or swelling, in the arteries of their hearts.
By Saturday night — when Newburger and 1,800 other worried pediatric specialists, including representatives from the Centers for Disease Control and Prevention and the National Institutes of Health, convened on a Zoom call to discuss the phenomenon — hospitals worldwide had identified about 100 similar cases. About half are in the United States.
‘‘Not in my lifetime have I seen anything remotely similar to what’s going on right now,’’ said Newburger, director of the cardiac neurodevelopment program at Boston Children’s Hospital.
The cases appeared to have some characteristics of a disease known as Kawasaki disease. The cardiologists, rheumatologists, and critical-care doctors in the meeting were also struck by their unusual timing and location. They started three to four weeks after the big wave of adult sickness, mostly in Europe and up and down the Eastern Seaboard of the United States, where COVID-19 had hit hard.
The number of affected children is still very small, relatively speaking, much lower than the number seriously ill from the flu during a similar time frame. And most have responded well to treatment.
‘‘I’m thinking of it kind of like the tip of the iceberg,’’ said Jane Burns, a professor of pediatrics at the University of California San Diego School of Medicine. ‘‘There’s this very small number of patients, thankfully, who are presenting with this shock syndrome, at the same time that there are a large number of patients in the same community,’’
Burns, along with other doctors, emphasized that parents should not panic. The vast majority of those younger than 18 who are infected have only mild symptoms or none at all. And researchers aren’t certain whether the condition is caused by COVID-19 or something else. Those with ‘‘pediatric multi-system inflammatory syndrome,’’ as doctors call the new illness, are ‘‘a small genetic subset of children who appear to be susceptible to this crazy thing,’’ she said.
But the strange nature of the cases in mostly previously healthy children, and its potential link to a virus that has delivered near-constant surprises, has put the medical community on high alert.
For more typical respiratory viruses such as influenza, children are often the first to become sick. COVID-19 is an anomaly, killing the elderly at high rates while leaving the very young mostly untouched. Only a handful of American children — including an infant and a 5-year-old who were children of first responders — have died of the disease.
Scientists have wondered whether children’s seeming powers against the virus are because they are more resistant to infection, or whether there is something protective in the biology of youth.
‘‘What we don’t know is whether, actually, they do carry the virus and transmit it without getting sick, or getting very mild symptoms” Togias said.