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Scientists examine kids' unique immune systems as more fall victim to COVID

Liz Szabo, Kaiser Health News on

Published in News & Features

Unanswered questions

Scientists have fewer clues about what goes wrong in certain children with COVID-19, said Kevan Herold, who teaches immunobiology at the Yale School of Medicine.

Research suggests that children have more robust innate immune systems than adults because they have experienced so many recent respiratory infections, within their first few years, which may prime their immune systems for subsequent attacks.

But not all children shrug off COVID-19 so easily, Eils said. Newborns haven’t been alive long enough to prime their immune systems for battle. Even toddlers may fail to mount a strong response, he said.

At Children’s Hospital New Orleans, half of COVID-19 patients are under 4, said Dr. Mark Kline, a specialist in infectious diseases and physician-in-chief.

“We’ve had babies as young as 7 weeks, 9 weeks old in the ICU on ventilators,” Kline said. “We had a 3-month-old who required ECMO,” or extracorporeal membrane oxygenation, in which the patient is connected to a machine similar to the heart-lung bypass machine used in open-heart surgery.

Even previously healthy children sometimes die from respiratory infections, from COVID-19 to influenza or respiratory syncytial virus.

But studies have found that 30% to 70% of children hospitalized with COVID-19 had underlying conditions that increase their risk, such as Down syndrome, obesity, lung disease, diabetes or immune deficiencies. Premature babies are also at higher risk, as are children who’ve undergone cancer treatment.

One thing hospitalized kids have in common is that almost none are vaccinated, said Dr. Mary Taylor, chair of pediatrics at the University of Mississippi Medical Center.

“There’s really no way to know which child with COVID will get a cold and be just fine and which child will be critically ill,” Taylor said. “It’s just a very helpless sensation for families to feel like there is nothing they can do for their child.”

Although scientists have identified genetic mutations associated with severe COVID-19, these variants are extremely rare.

Scientists have had more success illuminating why certain adults succumb to COVID-19.

Some cases of severe COVID-19 in adults, for example, have been tied to misguided antibodies that target interferons, rather than the coronavirus. An August study in ScienceImmunology reported that such “autoantibodies” contribute to 20% of COVID-19 deaths.

 

Autoantibodies are very rare in children and young adults, however, and unlikely to explain why some youngsters succumb to the disease, said study co-author Dr. Isabelle Meyts, a pediatric immunologist at the Catholic University of Leuven in Belgium.

Although hospitalizations are declining nationwide, some of the most serious consequences of infection are only now emerging.

Two months into the delta surge, hospitals throughout the South are seeing a second wave of children with a rare but life-threatening condition called multisystem inflammatory syndrome, or MIS-C.

Unlike kids who develop COVID-19 pneumonia — the major cause of hospitalizations among children — those with MIS-C typically have mild or asymptomatic infections but become very ill about a month later, developing symptoms such as nausea, vomiting, a rash, fever and diarrhea. Some develop blood clots and dangerously low blood pressure. More than 4,661 children have been diagnosed with MIS-C and 41 have died, according to the Centers for Disease Control and Prevention.

Although scientists still don’t know the exact cause of MIS-C, research by Yonker of Massachusetts General and others suggests that viral particles may leak from the gut into the bloodstream, causing a system reaction throughout the body.

It’s too soon to tell whether children who survive MIS-C will suffer lasting health problems, said Dr. Leigh Howard, a specialist in pediatric infectious diseases at Vanderbilt University Medical Center.

Although an August study in The Lancet shows that delta doubles the risk of hospitalization in adults, scientists don’t know whether that’s true for kids, said Dr. Anthony Fauci, the country’s top infectious disease official.

“We certainly don’t know at this point whether children have more severe disease, but we’re keeping our eye on it,” he said.

To protect children, Fauci urged parents to vaccinate themselves and children age 12 and up. As for children too young for COVID-19 shots, “the best way to keep them safe is to surround them by people who are vaccinated.”

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(KHN (Kaiser Health News) is a national newsroom that produces in-depth journalism about health issues. Together with Policy Analysis and Polling, KHN is one of the three major operating programs at KFF (Kaiser Family Foundation). KFF is an endowed nonprofit organization providing information on health issues to the nation.)

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