picture of abie martinez hospitalized with MIS-C side by side with picture of him 5 months later, smiling and dressed up
Left: Abie Martinez was in the hospital from January 29 to February 2, 2021. Right: Martinez in July, 2021.Courtesy of Abie Martinez and family
  • 15-year-old Abie Martinez is one of the 7,450 children and teens across the US who've developed MIS-C during the pandemic. 
  • MIS-C often develops 2-6 weeks after a COVID-19 infection, or exposure to COVID-19.
  • Doctors don't fully understand what causes the condition, or whether there might be some genetic factors at play. 

In January of 2021, Abie Martinez's body was in trouble.

What started out as red eyes, reminiscent of a pink eye infection, quickly progressed over the course of a few days to include high fever, diarrhea, vomiting, terrible back and leg pain, and an arm rash.

"My body just wasn't working," he said.

Soon, Martinez was being helicoptered in to Intermountain Primary Children's Hospital in Salt Lake City. Upon arrival, doctors discovered he was in a dangerous medical shock, unable to properly oxygenate his vital organs. His kidneys were injured, and his heart was too weak to squeeze normally. 

It was all indicative of multisystem inflammatory syndrome in children, MIS-C, prompted by a mild COVID-19 infection he'd had over a month earlier. He'd spend five days in the hospital, and several more months recovering at home, with a doctor's note to excuse him from gym, and a daily baby aspirin prescription to prevent clotting.  

Today, he says he's feeling much better and recovering well, though it is still difficult to run like he used to. 

"If I do a lot, I just tire myself out and then if I try and push myself more, it pains my chest," he said.

But he's off the aspirin, attending school dances, has been medically cleared to exercise again, and he even got a new job — a physical one — detailing cars at the car wash down the street from his house. 

"We're really fortunate," Martinez's mom, Cendy Marquez, said. "We're just happy that he was able to pull out of it."

There's no way to predict who gets MIS-C

Abie Martinez dancing with a little girl at a wedding
Martinez is recovering well from MIS-C, but says it is hard to run like he used to.Courtesy of Abie Martinez and family

Over the course of the pandemic, more than 7,450 kids like Martinez have developed MIS-C, according to the latest data from the Centers for Disease Control and Prevention. Sixty three of those children have died. Their cases are not linked to severe COVID-19. MIS-C can — and often does — happen even after an entirely asymptomatic infection of an otherwise healthy young person

"We don't know yet what the underlying mechanisms are that lead to development of MIS-C," Martinez's doctor, pediatric cardiologist Dr. Dongngan Truong, told Insider. "For some reason, in some kids, they have this hyper-inflammatory response to COVID-19 infection."

MIS-C doesn't happen right away, either. Often, it pops up anywhere from two to six weeks after the COVID-19 infection is over. And, Truong says, "it is not unusual" for kids who have MIS-C to be completely unaware they ever had the virus in the first place. 

"Oftentimes, they say they didn't know they had it at all or, you know, fever for one day, mild symptoms," she said.

Though the mechanisms of MIS-C (and its rarer adult companion, MIS-A) aren't well understood yet, there are some trends doctors have noticed. MIS-C is more common in boys (61% of cases), and an outsize proportion of the patients are Black (31%) and Latino (26%), numbers which, at least partially, reflect racial disparities in disease burden of COVID-19 across the US.

dr truong looking at heart images
Dr. Truong examining heart images with her colleague Dr. Adam Ware, another pediatric cardiologist. Here, they're looking at coronary arteries and assessing strain.Courtesy of Intermountain Primary Children’s Hospital

To better understand the syndrome, Truong and her colleagues are heading up a longitudinal study of more than 1,200 children and teens across North America who've had MIS-C during the pandemic, comparing heart images, looking for trends. Martinez is part of the 5-year study, he's one of about 70 MIS-C patients enrolled from Intermountain Primary Children's Hospital.

"The question is, is there some sort of underlying genetic susceptibility?" Truong said. 

Lately, she is seeing more new MIS-C cases as a result of the recent Omicron wave of infections. The volume of children coming in with MIS-C isn't nearly as high as what it was last winter, when Martinez was hospitalized, but there has been a noticeable uptick in cases.

"The idea of 'let's just get it, and get it over with' does make me nervous," the doctor said of people getting COVID-19.

Vaccination after MIS-C 

abie martinez getting vaccinated
Martinez completed his COVID-19 vaccine series in November, 2021.Courtesy of Abie Martinez and family

Currently, the CDC recommends that children who've had MIS-C wait at least 90 days to get vaccinated against COVID-19, and ensure that they've achieved a full cardiac recovery. After that, they may choose to get vaccinated, a decision often made in consultation with their doctor. 

Truong said among her patients, there's a "big spread" of feelings about COVID-19 vaccination. Some parents and kids who've had MIS-C are "eager" to get the vaccine, while others "express worry."

In Martinez's case, his mom said he could make the final decision about whether or not he wanted to get vaccinated. 

"Getting the vaccine, it doesn't prevent you from getting COVID, but it's like a lower risk of getting it," Martinez said.

He spoke with his doctor about the vaccine, and about how getting vaccinated further lowers your odds of getting sick again, even if you've been previously infected. For him, that risk-benefit analysis made COVID-19 vaccination a no brainer.

Even though "it's not a guaranteed thing," he said, if vaccination could reduce his odds of "going through that again," he was in. 

"He said, 'mom, I would much rather do the vaccine,'" Marquez remembered him saying. 

Doctors don't know yet whether getting MIS-C once makes you more susceptible to getting it again. But, there is limited evidence from recent studies in both the US and France that vaccines can help prevent more cases of MIS-C — especially the most severe cases, requiring life support and hospitalization. 

"I, personally, have not seen any MIS-C in kids who had been considered completely vaccinated," Truong said.

That doesn't mean it can't happen, but a recent study suggests the odds are vanishingly small, perhaps 1 in every 3 million — or less. 

In Martinez's case, "my arm was sore for like a day or two" after the vaccine, and then he was back to normal — working, going to school, and just generally getting "back to what I was" before COVID and subsequent MIS-C, he said. 

Read the original article on Business Insider