Multisystem inflammatory syndrome in children (MIS-C) is a group of symptoms linked to swollen, called inflamed, organs or tissues. People with MIS-C need care in the hospital.

MIS-C was first detected in April 2020. MIS-C is currently linked to coronavirus disease 2019 (COVID-19). Experts are still studying the cause of MIS-C and risk factors for getting it.

Most children who catch the COVID-19 virus have only a mild illness. But in children with MIS-C, after infection with the COVID-19 virus, the blood vessels, digestive system, skin or eyes become swollen and irritated.

MIS-C is rare. It most often happens within 2 months after having COVID-19. The child may have had a known infection. Or a close contact may have a confirmed infection.

Most children who have MIS-C eventually get better with medical care. But some kids quickly get worse. MIS-C can cause life-threatening illness or death.

Multisystem inflammatory syndrome in adults

Rarely, some adults develop symptoms similar to those of MIS-C. This is called multisystem inflammatory syndrome in adults (MIS-A).

It also is linked to a current or earlier infection with the virus that causes COVID-19. People with a prior infection may not have had serious symptoms.

Symptoms of multisystem inflammatory syndrome in children

The symptoms of MIS-C are serious and are treated in the hospital. Not all kids have the same symptoms. But if no other diagnosis fits, health care professionals may diagnose MIS-C if a child:

• Either had COVID-19 or has a close contact who had COVID-19 in the 2 months before hospitalization.
• Has a fever.
• Has a blood test result that shows a high level of inflammation throughout the body, called systemic inflammation.
• Has at least two of the following symptoms:
• Heart problems.
• Red, bloodshot eyes.
• Redness or swelling of the lips and tongue.
• Redness or swelling of the hands or feet.
• Pain in the belly, vomiting or diarrhea.
• Problems with blood clotting.
• Shock.

Emergency warning signs of MIS-C

Get help right away if your child has:

• Severe stomach pain.
• Pain or a feeling of pressure in the chest.
• Problems breathing.
• Pale gray or blue skin, lips or nail beds.
• New confusion.
• Inability to wake up or stay awake.

When to see a doctor

If your child has any of the emergency warning signs listed above, or is severely sick with other symptoms, get care right away. Take your child to the nearest emergency department or call 911 or your local emergency number.

If your child isn't severely ill but shows other symptoms of MIS-C, contact your child's health care professional right away for advice.

The health care team may want to do tests to check for areas of inflammation and other signs of MIS-C. These may include blood tests, or imaging tests of the chest, heart or abdomen.

The exact cause of MIS-C is not known yet. Many children with MIS-C have had a recent infection with the COVID-19 virus. Some may have a current infection with the virus.

One idea of a possible cause of MIS-C is that infection with the virus that causes COVID-19, either current or earlier, causes the immune system to overreact.

Children diagnosed with MIS-C are often between the ages of 5 and 11 years old. But cases are reported among children ages 1 to 15. A few cases have also happened in older kids and in babies.

MIS-C is thought to be a complication of COVID-19. Without early diagnosis and treatment, MIS-C can lead to severe problems with vital organs, such as the heart. In rare cases, MIS-C could lead to permanent damage or even death.

In the U.S., COVID-19 vaccines are now offered to people age 6 months and older.

A vaccine can prevent you or your child from getting or spreading the COVID-19 virus. If you or your child gets COVID-19, a COVID-19 vaccine could prevent you or your child from becoming seriously ill.

To prevent getting the COVID-19 virus and spreading it to others, the CDC recommends following these precautions:

• Keep hands clean. Wash hands often with soap and water for at least 20 seconds. If soap and water aren't available, use a hand sanitizer that has at least 60% alcohol.
• Avoid close contact with anyone who is sick. Avoid people who are coughing, sneezing or showing other signs that they might be sick and contagious.
• In public indoor spaces, keep distance between yourself and others. This is especially important in places with poor airflow.
• When COVID-19 community levels are high, wear a face mask in public indoor places. If your area has a high number of people with COVID-19 in the hospital, masks help prevent infection. The CDC suggests wearing the most protective mask possible that you'll wear regularly, fits well and is comfortable.
• Avoid touching your nose, eyes and mouth. Urge your child to follow your lead and avoid touching the face.
• Cover your mouth with a tissue or your elbow when you sneeze or cough. Throw away the used tissue. Wash your hands right away.
• Clean and disinfect high-touch surfaces regularly. This includes areas of your home such as doorknobs, light switches, remotes and keyboards.

Multisystem inflammatory syndrome in children (MIS-C) diagnosis is based on a child's symptoms and on ruling out similar conditions. Lab tests can help this process.

Providers rule out active cases of COVID-19 by testing for the virus with a swab of the nose. They also may swab the back of the throat. Providers also use blood tests to rule out inflammatory conditions such as Kawasaki disease, sepsis or toxic shock syndrome.

Many children with MIS-C test negative for a current infection with the COVID-19 virus. But proof of a prior infection can be gathered from an antibody test if a child had COVID-19 but didn't have any symptoms. It also can be collected by noting infections among a child's close contacts. Most kids who get MIS-C have a link to the virus that causes COVID-19 within 2 months of getting sick.

Providers also may order tests to look for inflammation and other signs of MIS-C:

• Lab tests, such as blood and urine tests, including tests for the level of an inflammatory protein in the blood.
• Imaging tests, such as a chest X-ray, an echocardiogram, an abdominal ultrasound or a CT scan.
• Other tests, depending on symptoms.

Children with MIS-C are treated in a hospital. Some need treatment in a pediatric intensive care unit. Treatment is supportive care and efforts to lower inflammation in any affected vital organs to protect them from permanent damage. Treatment depends on the type and severity of symptoms and which organs and other parts of the body are affected by inflammation.

Supportive care may include:

• Fluids, if levels are too low, a condition called dehydration.
• Oxygen to help with breathing.
• Blood pressure medicines to treat low blood pressure related to shock or to help with heart function.
• A breathing machine called a ventilator.
• Medicines that lower the risk of blood clots, such as aspirin or heparin.
• In very rare cases, extracorporeal membrane oxygenation (ECMO) using a machine that does the work of the heart and lungs.

Treatment to limit swelling and inflammation may include:

• Antibiotics.
• Steroid therapy.
• Intravenous immunoglobulin (IVIG), a blood product made up of antibodies.
• Other types of treatment, such as targeted therapies aimed at lowering high levels of proteins called cytokines, which can cause inflammation.

There is no proof that MIS-C is contagious. But there's a chance that your child could have an active infection with the COVID-19 virus or another type of contagious infection. So the hospital will use infection control measures while caring for your child.

If your child is seriously ill with MIS-C, you may feel overwhelming anxiety and fear. Because MIS-C is rare, you likely don't know anyone who has been through this experience. To help cope with the emotional toll this can take, ask for support. This can range from discussing your feelings with loved ones and friends to asking for help from a mental health professional. Ask your health care team for advice. For your own sake and that of your child, don't try to handle this anxiety and distress by yourself.

If your child has emergency warning signs of MIS-C or is severely sick, take your child to the nearest emergency department. Or call 911 or your local emergency number. Remember to wear a mask to protect yourself and others.

If your child's symptoms are not severe, contact your child's pediatrician or other health care professional. The provider may want to assess your child or refer you to a provider who specializes in infectious diseases.

Here's some information to help you get ready for your appointment.

What you can do

When you make the appointment, ask if there's anything you need to do in advance. Make a list of:

• Your child's symptoms, including when they started.
• Key personal information, including major stresses, recent life changes and family medical history.
• All medicines, vitamins or other supplements your child takes, including the dosages.
• Any group activities your child recently took part in, including the dates.
• Questions to ask the health care professional.

What to expect from your doctor

Your health care professional is likely to ask you, and your child, depending on your child's age, several questions, such as:

• When did the symptoms begin?
• How severe are the symptoms?
• Has your child been tested for COVID-19?
• Has your child been exposed to anyone who tested positive for the COVID-19 virus?
• Does your child go to school?
• Has your child been involved in any recent group activities, such as sports?
• Who has your child been in close contact with recently?

Preparing for the appointment makes sure you have time to get all of your questions answered. It helps you learn what the next steps are and why they're important.