Multi-system inflammatory syndrome in children is a rare condition in which different parts of the body - including the heart, lungs, kidneys, brain, skin, eyes or gastrointestinal organs - become inflamed.
MIS-C, which most often appears four to six weeks after a COVID infection, can be serious and potentially deadly, but most children who are diagnosed with it recover with medical care, according to the Centers for Disease Control and Prevention.
Pediatric immunologist with the Washington University School of Medicine Megan Cooper told Eyewitness News many of her patients didn't even know they had COVID until they started feeling the after effects of MIS-C.
"I see kids with MIS-C and [it's] really just like nothing I've seen in my career before," she said. "This is not the flu. This is not a bad cold."
Jackson Thorn, 12, was one of those children in Southern California impacted.
READ ALSO | 13-year-old Chicago boy nearly dies from COVID; mom regrets not getting son vaccinated
"My head started hurting and my stomach started hurting," he said. "I felt scared because I didn't know what was wrong with me."
His mom, Amy Polly, said he woke up in the middle of the night one day and was wheezing. Jackson had to spend 8 days in the hospital which included a 10-hour IV infusion therapy followed by two weeks of taking steroids.
He has since recovered.
Experts continue to emphasize the urgency for not only children to be vaccinated, when eligible, but also for their parents and all of those in the communities around them to get the shot as soon as possible.
According to the CDC, you should contact your child's doctor right away if your child is showing the following symptoms of MIS-C:
Ongoing fever PLUS more than one of the following:
- Stomach pain
- Bloodshot eyes
- Dizziness or lightheadedness (signs of low blood pressure)
- Skin rash
The CDC says the best way for a parent to protect their child is by taking "everyday actions" to prevent COVID-19, including mask-wearing and hand-washing.