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Medical experts are learning more about rare syndrome that affects children. Getty Images
  • COVID-19 is a respiratory disease, but PMIS (also known as multisystem inflammatory syndrome in children, or MIS-C) affects organs and blood vessels.
  • Not all children with PMIS have had COVID-19, though many test positive or show coronavirus antibodies.
  • Kids make up about 1.7 percent of COVID-19 cases in the United States.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.

Parents across the nation are watching their children closely for a rare syndrome linked to COVID-19.

The first alert of this syndrome was reported just a few weeks ago, but now health experts across the globe are warning that parents should look for symptoms of pediatric multisystem inflammatory syndrome (PMIS).

Children with PMIS experience an immune response that affects blood vessels and arteries, leading to inflammation that can cause heart damage.

Though rare, the condition has been emerging in kids around the world. Today, New York City Mayor Bill de Blasio said the Centers for Disease Control and Prevention (CDC) confirmed that 145 cases of the syndrome are linked to COVID-19.

COVID-19 is a respiratory disease, but PMIS (also known as multisystem inflammatory syndrome in children, or MIS-C) affects organs and blood vessels.

Unlike COVID-19, PMIS isn’t known to be contagious.

Symptoms of PMIS are similar to Kawasaki disease, which is characterized by inflamed blood vessels and toxic shock syndrome.

These symptoms include:

  • fever that lasts more than 5 days and gets higher
  • severe abdominal pain, vomiting, or diarrhea
  • bloodshot eyes
  • skin rash
  • change in skin color, which can include becoming pale, patchy, or blue
  • difficulty feeding or too sick to drink
  • trouble breathing or quick breathing
  • chest pain or racing heart
  • confusion, irritability, or lethargy

Dr. Roberta DeBiasi, chief of infectious diseases at Children’s National Hospital in Washington, D.C., explains the following are also symptoms that should send a red flag to parents:

  • swelling and redness in the hands and feet
  • redness or cracking in the lips or tongue
  • swollen lymph nodes in the neck

Kawasaki disease leads to artery inflammation and can damage the heart. It’s usually found in children under the age of 5 and can be treated if discovered before it causes long-term effects, such as heart damage.

Kawasaki disease is the most common cause of heart disease in children. Kawasaki disease shock syndrome (KDSS) refers to children with the disease who have hypotension, or low blood pressure.

A bacterial infection causes toxic shock syndrome. It presents with similar symptoms as Kawasaki disease, but the two have different treatments.

PMIS is a postinfectious syndrome, so it’s not contagious, notes Dr. Charles L. Schleien, chairman of the department of pediatrics at the Steven & Alexandra Cohen Children’s Medical Center in New York.

This also means the syndrome develops after COVID-19 has likely passed.

“There is a strong association between PMIS and COVID-19 in terms of timing as well as geographical association,” Dr. Sam Dominguez and Dr. Sean O’Leary, pediatric infectious disease specialists at Children’s Hospital Colorado, told Healthline.

“There is a suggestive relationship between the two. However, this is a new and evolving situation, and we are continuing to monitor and learn more about it,” they said.

The number of children experiencing PMIS who also have COVID-19, as well as the fact that many children with PMIS live in areas hard-hit by the new coronavirus, was enough to convince Dr. Lauren Henderson, a rheumatologist at Boston Children’s, that the two are linked.

“There is a clear temporal association between PMIS in children and COVID-19,” she told Healthline.

This new syndrome has occurred at the same time that COVID-19 is circulating widely, which makes it highly likely that the two are related, agrees DeBiasi.

Previously, COVID-19 was thought not to affect children as frequently or as severely as it does adults.

“We still aren’t clear why the kids have been generally unaffected directly by COVID-19 compared to adults,” Schleien told Healthline. “We are also unclear why this postinfectious Kawasaki-like syndrome is appearing.”

Most children with COVID-19 are either asymptomatic or have mild symptoms. Some children have been hospitalized and some have died from the virus, but that’s rare, Dominguez and O’Leary note.

Kids make up about 1.7 percent of COVID-19 cases in the United States.

A May 13 study published in The Lancet shares research on clusters of children — namely in the United Kingdom and Italy — who experienced PMIS.

In the United States, at least 17 states and Washington, D.C., have reported children with PMIS symptoms. In New York City, 55 of the 100 cases identified were in children who tested positive for COVID-19 or virus antibodies.

Most pediatric patients who have had COVID-19 haven’t developed PMIS, DeBiasi notes. Her hospital has seen more than 275 symptomatic children who tested positive for COVID-19. Of those, five children met the criteria for PMIS.

Doctors are sharing guidance on how to respond to children with PMIS. On May 14, the CDC shared a statement acknowledging the condition.

Doctors combine a clinical exam and laboratory studies to diagnosis PMIS. Sometimes they’ll do radiology-based tests.

“It is difficult to tell if a child has PMIS just from a fever and rash because many other infections can cause fever and rash,” Henderson said.

That’s why it’s important to see a doctor if your child shows symptoms.

Schleien says PMIS is treatable — unlike COVID-19, which isn’t directly treatable.

Mostly, physicians will treat PMIS with intravenous (IV) immunoglobulin and aspirin. Steroids can be used, too, says Dr. Audrey R. Odom John, chief of the division of pediatric infectious diseases at Children’s Hospital of Philadelphia.

Children with PMIS also usually require support in intensive care units, often to help maintain blood pressure. “Catching this early can likely result in better outcomes,” Dominguez and O’Leary said.

Many children go home and are healthy after treatment. But missed cases have a greater chance of long-term problems for children, Schleien adds.

“Often, fevers will resolve the same day as the treatment, and the heart dysfunction typically gets better over several days, and they appear to do very well,” John said.

Children need to be followed to assess long-term risks, though.

Children and young adults are at a greater risk for severe complications from COVID-19 than previously thought, and those with underlying health conditions are at an even higher risk, according to a study in JAMA Pediatrics.

The study documented seriously ill pediatric COVID-19 patients in North America but didn’t cover PMIS specifically. It was written before PMIS was described.

The study followed 48 children treated for COVID-19 over a 3-week span in March and April. More than 80 percent of them had underlying health conditions, such as diabetes, obesity, or immune suppression.

Of those, 40 percent relied on technological support due to developmental delays or genetic anomalies.

More than 20 percent of the children experienced organ failure in more than two organs, and almost 40 percent needed ventilator and breathing tube support.

At the end of the study, about 33 percent of them were still hospitalized with the virus. Two of the children died.

DeBiasi says researchers are looking into which underlying conditions as well as what racial, ethnic, and genetic backgrounds may make COVID-19 more severe.

“We need to study more about the different strains of virus that have circulated in the U.S., Europe, and China, and understand if the virus is changing appreciably and, if so, if this has any correlation with the types of illness we are seeing,” DeBiasi said.

If your child shows signs of severe COVID-19 or PMIS, call your doctor.

“Parents should contact their primary care physician, but if symptoms seem severe, then they should bring their child to the emergency department,” DeBiasi advised.

“We don’t want parents to panic,” DeBiasi added. “We believe that the vast majority of children will have mild symptoms with this infection, but parents should trust their instincts. If [they] feel that their child is very ill, they should not delay seeking care with the belief that children cannot get very ill from this infection.”

“While PMIS is very scary, we are learning more about it every day,” added Dr. Steven Horwitz, assistant professor of pediatrics at Rutgers Robert Wood Johnson Medical School.

He’s currently working with Boston Children’s Hospital and the CDC on a national multisite study to explore PMIS.

“The overwhelming majority of patients, even the sickest ones, are responding to treatment and recovering,” he said.