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Lingering COVID Virus in the Gut May Lead to Mis-C in Kids

Child wearing a face mask.

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Key Takeaways

  • Researchers identified that viral particles that stay in the gut after a COVID-19 infection may cause multisystem inflammatory syndrome in children (MIS-C).
  • A drug previously used to treat celiac disease may prove to be a viable treatment option.
  • Experts say finding the cause of MIS-C is crucial for developing treatments.

A new study is shedding light on how the rare and serious COVID-19 complication multisystem inflammatory syndrome in children (MIS-C) develops. According to the research, viral particles that stay in the gut after a COVID-19 infection can travel to the bloodstream, causing the condition.

The May study, which was published in the Journal of Clinical Investigation, analyzed levels of SARS-CoV-2, the virus that causes COVID-19, in the blood and stools of 100 children. Of those children, 19 had MIS-C, 26 had COVID-19, and 55 were healthy.

The researchers found high levels of SARS-CoV-2 virus in 95% of the stools of children with MIS-C, along with high levels of zonulin, a protein that determines how permeable the digestive tract is.

The team theorized that SARS-CoV-2 viral particles found in the gastrointestinal tract of children move into the bloodstream, leading to the inflammatory immune response that happens with MIS-C.

“We show that SARS-CoV-2 antigens are detected in the blood, and most likely are coming from the gut, given the virus’ presence in the stool and markers of gut barrier integrity breakdown,” lead study author Lael Yonker, MD, a pediatric pulmonologist at Massachusetts General Hospital, tells Verywell. “Understanding the mechanism is important because, for the first time, we can target the cause of MIS-C by developing specific treatments or preventive therapeutic strategies.”

What is MIS-C?

With MIS-C different body parts can become inflamed, including the heart, lungs, kidneys, brain, skin, eyes, or gastrointestinal organs. It’s not entirely clear at this point what causes MIS-C, but many children who have the condition tested positive for SARS-CoV-2 or were around someone with COVID-19.

MIS-C is “not a benign disorder. A lot of the kids who have it will have very severe complications, including cardiac complications,” Danelle Fisher, MD, FAAP, a pediatrician and chair of pediatrics at Providence Saint John’s Health Center in California, tells Verywell.

Symptoms of MIS-C can vary but may include:

  • Abdominal pain
  • Vomiting
  • Diarrhea
  • Neck pain
  • Rash
  • Bloodshot eyes
  • Fatigue

Right now, doctors typically provide supportive care for symptoms, like medicine or fluids to make a child feel better. Medications targeting inflammation may be used. But Fisher stresses that figuring out why MIS-C happens is the “important first step” toward treating it effectively.

Determining the Cause Can lead to new treatment

“Children who have recovered from COVID may experience MIS-C, which can cause serious symptoms and can result in death,” study author David R. Walt, PhD, a core faculty member at the Wyss Institute at Harvard University and co-director of the Mass General Brigham Center for COVID Innovation, tells Verywell. “If we understand the mechanism, we may be able to prevent more severe forms of the syndrome.”

Co-senior author Alessio Fasano, MD, head of Massachusetts General Hospital’s Division of Pediatric Gastroenterology and Nutrition, suggested using larazotide acetate, a drug he previously developed to treat celiac disease, to treat MIS-C.

"[Larazotide] blocks the breakdown of tight junctions in the gut,” Fasano tells Verywell. “Since we think the viral particles are coming from the gut and leaking into the blood through the gut lining, by preventing this ‘leak’ through the gut with larazotide, we saw a reduction in viral particles in the blood. With fewer viral particles in the blood, the hyperimmune responses that define MIS-C can resolve. “  

The team obtained compassionate use permission for larazotide from the Food and Drug Administration (FDA), and successfully treated a 17-month-old MIS-C patient with the drug.

The researchers are planning to conduct a clinical trial on the effects of larazotide on patients with MIS-C. “We hope to develop an effective treatment, and potentially even a preventive treatment, for MIS-C so that children won’t get so sick from COVID-19 infections,” Yonker says.

That could be a game-changer, Juan C. Salazar, MD, MPH, physician-in-chief and executive vice president of academic affairs at Connecticut Children's Medical Center who has been conducting separate research on MIS-C, tells Verywell.

He says doctors “have to be so much more nimble and quick to make the diagnosis of MIS-C” given how devastating the results can be. Currently, MIS-C is treated with a combination of steroids and IV hemoglobin, but having “more specific therapies is crucial,” Salazar adds.

What This Means For You

If your child is exhibiting symptoms of COVID-19 or MIS-C, it's important to seek emergency care right away by calling 911 or going to your local emergency facility. Watch out for emergency warning signs such as breathing difficulties, chest pain or pressure, severe abdominal pain, and/or pale, gray, or blue-colored skin, lips, or nails.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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  1. Yonker LM, Gilboa T, Ogata AF, et al. Multisystem inflammatory syndrome in children is driven by zonulin-dependent loss of gut mucosal barrier. Journal of Clinical Investigation. May 25, 2021. doi: 10.1172/JCI149633

  2. Multisystem Inflammatory Syndrome (MIS-C). Centers for Disease Control and Prevention. February 25, 2021.

  3. Centers for Disease Control and Prevention. Multisystem inflammatory syndrome (MIS-C). Updated February 25, 2021.