At the onset of the coronavirus pandemic it appeared that young people were largely spared from the virus. Now, doctors believe there's growing evidence that a rare, mysterious illness appearing in children may be linked to the virus.
It's been dubbed Pediatric Multisystem Inflammatory Syndrome, abbreviated as PMIS or PIMS. The U.S. Centers for Disease Control and Prevention issued an advisory to doctors about it Thursday afternoon, referring to the condition as Multisystem Inflammatory Syndrome in Children (MIS-C) Associated with Coronavirus Disease 2019 (COVID-19).
Symptoms of the syndrome have been compared to those of Kawasaki disease and toxic-shock syndrome. PMIS, however, is being recognized as a "new entity," according to Dr. Luiza Petre, a cardiologist and professor of cardiology at Mount Sinai's School of Medicine in New York.
Kawasaki disease is a rare but serious illness believed to be triggered by the immune system's response to infection, but an official cause is unknown.
Children with Kawasaki experience a prolonged fever lasting several days, a skin rash and swollen lymph nodes in the neck; affected children can also develop redness in their eyes, lips, mouth, as well as the palms of their hands and soles of their feet, according to the National Institutes of Health. Most children recover, but if left untreated, Kawasaki can cause cardiac issues and become life-threatening. Toxic shock also causes fever and a decrease in blood flow, but is triggered by a bacterial infection.
While an understanding of PMIS is still evolving, children with the syndrome also experience a prolonged fever, rashes, change in the color of their skin or their lips, swollen glands and red eyes. What differentiates PMIS from Kawasaki appears to be complaints of abdominal pain, as well as nausea, vomiting, diarrhea and chest pain.
"What we're seeing is the immune system is actually going into overdrive, impacting the body in a negative way," Dr. Jake Kleinmahon, a pediatric oncologist at Ochsner Hospital for Children, in New Orleans, who has treated several children for the illness, told CBS News. "Some of these patients are having inflammation of their coronary arteries, and you can have basically a heart attack."
According to Dr. Sean O'Leary, vice chair of the American Academy of Pediatrics' Committee on Infectious Diseases, the level of inflammation in the heart tends to be higher with PMIS, as compared to Kawasaki disease.
All together, the syndrome has shown to be more severe than Kawasaki. "That's what's concerning," Petre told CBSN. "And a lot of (PMIS) cases do require ICU, almost 80% of them."
PMIS has been reported in over 100 children in New York, the epicenter of the U.S. coronavirus outbreak. CBS News has tallied about 200 cases under investigation in 19 states and Washington, D.C., and cases have also been reported in at least six other countries.
Doctors in Italy published a study Wednesday documenting numerous cases of PMIS linked to the coronavirus. Eight out of 10 children they studied with PMIS had antibodies to COVID-19, indicating that they had been infected.
The fact that the syndrome is appearing in places where coronavirus is prevalent suggests that there could be a correlation, O'Leary said. He cautioned, however, that it's still too early to say anything for certain: "Some of the things I tell you will be true tomorrow, but some of them may not," he said.
CBS News senior medical correspondent Dr. Tara Narula said, "It's important to stress that in the grand scheme of the pandemic, this is rare. We're still learning a lot more about it."
A majority of the children with PMIS symptoms reported in New York have also tested positive for COVID-19, but others have not. "That is something we doctors don't have an explanation for," Petre said.
"If we talk about the frequency of Kawasaki disease, even the specialists in this disease say they've never seen more than five cases at once in one hospital," she said. "So that's something definitely suspicious about the timing between COVID and these cases."
According to O'Leary, PMIS cases seem to appear about a month after a peak of COVID-19 cases in an area. If the syndrome is brought on by a COVID-19 infection, the lag time for PMIS symptoms is a curious feature, he said. "It's almost more surprising that most of these kids are (COVID-19) positive."
"That's the mystery, it's a lot like a delayed reaction," Petre said of the symptoms' onset.
If a child does present with PMIS symptoms, it is important to contact your doctor. According to Petre, if a child has a fever that doesn't go down and is resistant to medication for more than a day, a doctor should be contacted.
The American Academy of Pediatrics released guidelines for parents earlier this week advising them to call their pediatrician if they notice any of the following symptoms:
"In this syndrome early intervention is critical as children can decompensate very quickly, and they should seek medical attention immediately," Petre said.
According to Petre and O'Leary, if a child is admitted for PMIS, their primary treatment will be supportive care. Fluids and medication would likely be administered to maintain blood pressure, as well as anti-inflammatory medication like steroids or immunoglobulin (IVIG).
"If you're not really aware of this syndrome that's being described, it could easily be missed," said Kleinmahon. "Fortunately children overall are very resilient. And almost all of the cases, if we're able to knock down the inflammation and get them past the beginning stages of this, they're usually doing very well."