New study shows COVID vaccination safe for kids diagnosed with severe inflammatory condition after a coronavirus infection

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Most children fully recover from a COVID-19 infection with few or no medical complications.

But about 9,333 kids and teens across the U.S. have developed multisystem inflammatory syndrome — MIS-C for short — during the pandemic. It’s a rare, but serious condition that occurs several weeks after a COVID-19 infection.

Dr. Matthew Elias, a pediatric cardiologist at Children’s Hospital of Philadelphia, said kids will come into the hospital with fever, gastrointestinal symptoms, and rashes. In some cases, the condition can be life threatening and cause heart problems and organ failure.

“MIS-C involves an abnormal immune response to the SARS-CoV-2 infection,” Elias said. “Would the vaccine then lead to a severe inflammatory response, would it lead to the recurrence of MIS-C, would it lead to myocarditis after the vaccine?”

Elias is a co-author of new research that sheds light on those questions. A national study showed that COVID-19 vaccination in children and teens after they’ve been diagnosed with MIS-C is safe, and it does not cause a recurrence of the inflammatory syndrome.  Scientists at 22 medical centers looked at 385 patients ages 5 and older with a prior diagnosis of MIS-C.

“This data hopefully will be very reassuring to families and to health care providers when considering the vaccine,” he said.

A majority of kids who end up with MIS-C do eventually go home from the hospital. However, 76 children in the U.S. have died from the condition.

Experts say COVID-19 vaccines can help reduce the risks of developing any long-term coronavirus complications, which is why Elias suggested that all kids who are eligible for a vaccine get one, including those who’ve survived MIS-C.

Guidance from the U.S. Centers for Disease Control and Prevention recommends that kids wait 90 days after a MIS-C diagnosis before getting a COVID-19 vaccine.

Elias said there’s still much to learn about MIS-C as a long COVID condition, like why some kids develop it and others do not.

“Every few months, there’s a new variant with different initials on the news,” he said. “[We’re] trying to determine, is that going to lead to more or fewer cases of MIS-C? How will their hearts be involved with that, with any future variants and with MIS-C?”

The latest vaccine study and its findings are part of the larger ongoing Long-Term Outcomes After the Multisystem Inflammatory Syndrome in Children, or MUSIC study, funded by the National Heart, Lung, and Blood Institute.