Utah’s Primary Children’s Hospital will help lead 5-year study of a mystery illness that strikes children who get COVID-19

Primary has seen more than 50 cases of MIS-C in children after they fought the coronavirus.

Madilyn Dayton said she is mostly, but not entirely, recovered from the effects of a mysterious illness that strikes some children after they have had COVID-19.

“I still get tired a lot, easily,” Dayton, 13, said Tuesday from her home in Cokeville, Wyo. “Other than that, everything has gone almost back to normal.”

Dayton’s mother, Marilyn, said her daughter, three months after being hospitalized, suffers from chronic fatigue. “I’m blaming it on COVID. I’m hoping it’s not the teenage hormones kicking in,” Marilyn Dayton said, as her mortified daughter smiled.

The illness — called multisystem inflammatory syndrome in children, or MIS-C — is now the subject of a five-year nationwide study, the first of its kind in the United States, being launched by Utah’s Primary Children’s Hospital and Boston Children’s Hospital. And the Daytons are taking part in it.

“Parents ask me all the time, in the clinic and in the hospital: What can we expect over time? How will my child do over time? Or, how will my child’s heart be affected in the future?” said Dr. Ngan Truong, a pediatric cardiologist at University of Utah Health and Intermountain Primary Children’s Hospital, during a Tuesday news conference announcing the study.

“Unfortunately, I don’t have an answer for them at this point. And the data that we have is very limited right now,” Truong said. “However, I hope that in the coming years, we’ll have more answers for parents and for my patients.”

The illness is believed to be triggered when the body’s immune system overreacts in battling the coronavirus. It mostly affects children’s hearts and circulatory systems, leading to enlarged arteries, low blood pressure and reduced heart function.

Primary Children’s Hospital has seen at least 50 cases of the illness, Truong said.

As of Jan. 8, according to the federal Centers for Disease Control and Prevention, 1,659 children across the country have been diagnosed with MIS-C — and 26 children have died from it. Most were children between 1 and 14, with an average age of 8. Most develop the illness 2 to 4 weeks after being infected with the coronavirus.

Truong noted that MIS-C strikes Black and Latino children disproportionately. The CDC reports 37% of cases are among Latino and Hispanic patients, and 34% are among Black children.

The MUSIC study will follow MIS-C patients over the next five years, collecting data from their hospital visits — which usually happen two weeks, two months and six months after infection — and from a questionnaire by phone once a year.

Truong and her co-lead investigator, Dr. Jane Newberger at Boston Children’s Hospital, hope to enroll 600 young patients in the United States and Canada to take part in the study. Some 30 hospitals will be part of the study.

When the Daytons were asked to take part in the study, Marilyn Dayton “never had any doubts ... because this is such an unknown disease in children. [When Madilyn was hospitalized,] I wanted answers. … What are the long-term effects? Can she get back to playing sports? When can she be back to normal?”

Madilyn Dayton had been feeling sick for a couple of days last October when she woke up one morning unable to move. The family didn’t know Madilyn had contracted the coronavirus — it apparently came and went without symptoms — but the aftermath of MIS-C put Madilyn in Primary Children’s intensive care unit.

Doctors, Truong said, are advising young athletes who are diagnosed with MIS-C to avoid sports or other strenuous activity for three to six months to avoid scarring of the heart.

Madilyn is studying from home because “I don’t know if she could get out and do a full day of school,” Marilyn Dayton said. Madilyn occasionally has met with her teammates to shoot baskets, “but it was within, like, the first five minutes of shooting around that her face just went pale and she was very winded,” her mother said.