Coronavirus cases and hospitalizations among children are at an all-time high, prompting worries over a rare but serious syndrome that shows up in kids several weeks after COVID-19 infections.
MIS-C, or multisystem inflammatory syndrome in children, is a condition associated with COVID-19 in which different parts of the body become inflamed, including the heart, lungs, kidneys, brain, skin, eyes or gastrointestinal organs, according to the Centers for Disease Control and Prevention. The cause of the syndrome is not known.
The syndrome typically shows up two to six weeks after COVID-19 infection, and its symptoms include fever, stomach pain, bloodshot eyes, diarrhea, dizziness, skin rash and vomiting.
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While MIS-C is rare – the CDC has documented over 6,400 MIS-C cases and 55 deaths as of Jan. 3. – the current surge of coronavirus cases among children likely means more MIS-C cases will soon show up.
“If you have more children getting [COVID-19] then you’ll end up seeing more MIS-C,” says Sophie Katz of the Vanderbilt University Medical Center. “I think that’s just what’s going to happen.”
The CDC reports that the median age of patients with MIS-C was 9 years old, and half of the children with the syndrome were between the ages of 5 and 13 years old. The majority of reported patients were male.
MIS-C has been reported in every state. Georgia and California report the most cases, at over 400.
Of particular concern with MIS-C is inflammation of the heart.
“Whenever that happens, usually we see children who are pretty seriously ill – kind of in shock – and their heart … doesn’t pump quite as well as it normally should,” says Katz, who is an assistant professor of pediatric infectious diseases.
The average hospitalization stay with MIS-C is five days. Katz says that around 98% of patients with MIS-C are back to normal by their one-month check up.
Most patients do well with treatment, which can include intravenous immunoglobulin and steroids, according to Katz.
But with more children getting coronavirus as the highly transmissible omicron variant spreads, more are likely to get MIS-C, too.
“Every pediatrician I know is anxious that we’re going to see large surges in both [COVID-19] and MIS-C cases after [the holidays],” Wendy Hasson, a pediatric intensive care unit doctor in Portland, Oregon, who is also a spokesperson for the American Academy of Pediatrics, told U.S. News last month.
So when will experts know if omicron leads to an increase in MIS-C? Katz says a spike would be delayed three to four weeks after a coronavirus surge.
“I am sort of bracing myself for higher numbers of MIS-C with this omicron wave in about a month or so,” Katz says.
Coronavirus cases among kids are at “the highest case count ever reported since the start of the pandemic,” according to a report from the American Academy of Pediatrics and the Children’s Hospital Association.
More than 325,000 pediatric infections were reported in the week leading up to Dec. 30, according to the report. That’s nearly a 65% increase over the week prior.
“Nearly 7.9 million children have tested positive for COVID-19 since the onset of the pandemic, representing over 1 in 10 US children,” the report said.
Despite already reaching record levels, more infections among children are expected, experts warn.
Leading infectious disease expert Anthony Fauci this week said that while the highly contagious omicron variant appears to cause a more mild disease than delta, “the sheer volume of infections because of its profound transmissibility mean that many more children will get infected.”
“As many more children will get infected, a certain proportion of them – usually children that have underlying comorbidities – are going to wind up in the hospital,” Fauci said during a press briefing. “That is just an inevitability.”
Something to watch, Katz says, is more MIS-C cases popping up in kids who did not know they previously had COVID-19. Many MIS-C cases occur in kids who had mild COVID-19 symptoms or who were asymptomatic, and that trend is expected to continue with the omicron variant.
While the CDC has encouraged parents to get their kids vaccinated against the coronavirus in order to protect against MIS-C, vaccination rates among children remain well below what experts would like to see.
Only 16% of kids 5-11 are fully vaccinated, and just over half of kids ages 12-17 are fully vaccinated, according to CDC data. A vaccine has not yet been authorized for children under the age of 5.
Vaccine uptake among 5- to 11-year-olds and 12- to 17-year-olds has significantly slowed, according to a survey from Kaiser Family Foundation published last month.
A new study published by the CDC on Friday found that the Pfizer coronavirus vaccine was highly effective at preventing MIS-C in children ages 12-18.
Among the 102 MIS-C cases the study examined, 95% of patients were unvaccinated. All of the patients who needed life support were unvaccinated, according to the study.
“This analysis lends supportive evidence that vaccination of children and adolescents is highly protective against MIS-C and COVID-19 and underscores the importance of vaccination of all eligible children,” the researchers wrote.