Multisystem Inflammatory Syndrome in Children (MIS-C)

Confirmed MIS-C cases in California 2020–2023

Background

In the Spring of 2020, doctors noticed that some children who had recently had COVID-19 were getting very sick with a new illness. This illness was called Multisystem Inflammatory Syndrome in Children (MIS-C). It caused symptoms like fever, inflammation throughout the body, and problems in multiple body systems, which were serious enough to require hospitalization. The number of MIS-C cases was highest in 2020 and went down a lot over the next three years. By 2024, fewer than 10 cases were reported each year in California.

MIS-C only affects people who are under 21 years old, and most cases happen in school-aged children. We still don’t know why some children get this illness after COVID-19 and why it has become so rare. Other infections, like chickenpox and strep throat, can also lead to inflammatory diseases after recovery. To learn more about MIS-C, including its causes, best treatments, and outcomes, the California Department of Public Health (CDPH) works with the CDC to keep track of cases.

Symptoms

Most patients with MIS-C have a history of COVID-19 infections, often with few or no symptoms. The disease can start several weeks after the infection and most commonly starts with a new or returning fever. Other symptoms may include:

• rash
• pink eye
• abdominal pain
• diarrhea
• vomiting

While many of these symptoms are typical of other common pediatric illness, children with MIS-C will eventually become more severely ill. If you or your child develops these worsening symptoms you seek emergency medical care immediately

• Trouble breathing
• Pain or pressure in the chest that does not go away
• Confusion or unusual behavior
• Severe abdominal pain
• Inability to wake or stay awake
• Pale, gray, or blue-colored skin, lips, or nail beds (depending on skin tone)

Prevention

COVID-19 vaccinations can help protect your child from MIS-C. To keep your child safe, it's important to make sure they get all their COVID-19 vaccines on time.

Reporting MIS-C Cases

Clinicians should report to the patient’s local health department (LHD) any person <21 years of age who is hospitalized following a recent COVID-19 positive test (or known exposure) and who has:

• fever
• elevated CRP
• more than one organ system involved

Often affected children look indistinguishable from Kawasaki Disease and may in fact meet the definition for both illnesses.

Assist the LHD in obtaining medical records sufficient for them to complete the MIS-C case reporting form.

Please also report any person <21 years whose death certificate lists MIS-C as a cause of death or a condition contributing to death.

Email CDPH at CovMis-c@cdph.ca.gov

Resources

• Clinical Overview of Multisystem Inflammatory Syndrome in Children (MIS-C) (CDC)
• MIS-C Case Report Form (PDF)(CDC)
• CDC/CSTE 2023 MIS-C Case Definition (CDC)
  
• CDPH MIS-C Quicksheet (PDF)